Currently, the most widely used potent teratogen is __________.

Correct Answer: D

Rationale: The correct answer is D, isotretinoin. Isotretinoin is a medication commonly used to treat severe acne, but it is a potent teratogen, meaning it can cause severe birth defects if taken during pregnancy. Aspirin (choice A) is not a widely used potent teratogen. Diethylstilbestrol (DES) (choice B) was a known teratogen, but it is not currently widely used. Thalidomide (choice C) was another historical teratogen, but it is also not currently widely used. Therefore, isotretinoin is the most relevant answer as it is a commonly used medication that poses a high risk of birth defects if used during pregnancy.

Correct Answer: C

Rationale: Three-month-old Jefferson will likely listen longer to human speech compared to nonspeech sounds because infants have a natural preference for speech sounds. This preference is believed to be attributed to their biological readiness to learn language and communicate with others. Choice A is incorrect because voices are a form of human speech, which is preferred over pure tones. Choice B is incorrect as noises do not necessarily engage infants' attention as effectively as human speech. Choice D is incorrect because Jefferson is more likely to listen longer to his native language rather than a foreign language at this early age.

Correct Answer: D

Rationale: Sensitivity to touch emerges early prenatally and is well-developed at birth. Newborn babies have a well-developed sense of touch, which is crucial for bonding with their caregivers and exploring their environment. This sensitivity to touch helps babies respond to comforting sensations such as gentle strokes and cuddles. Visual acuity, color vision, and depth perception are sensory capabilities that develop and mature after birth, not prenatally. While important for interacting with the environment, they are not as well-developed at birth as sensitivity to touch.

Correct Answer: C

Rationale: According to research, mothers who are supported by a trained companion during childbirth have fewer birth complications and shorter labors. This support can reduce stress and anxiety levels, provide comfort and encouragement, and help the mother feel more in control during labor and delivery. Overall, having a trained companion present can contribute to a more positive childbirth experience for the mother. Choices A, B, and D are incorrect because they do not align with the research findings that specifically highlight the benefits of having a trained companion during childbirth.

Correct Answer: B

Rationale: The correct answer is B: 'Helps keep the temperature of the prenatal world constant.' Amniotic fluid helps maintain a stable and warm environment for the developing organism, assisting in regulating the temperature. This fluid also acts as a cushion, protecting the fetus from physical harm. Choices A, C, and D are incorrect because while amniotic fluid provides protection and support to the developing organism, it does not directly deliver food, oxygen, nutrients, or remove waste products, nor does it produce blood cells as the organs eventually take over this function.

Correct Answer: B

Rationale: In the last weeks of pregnancy, most fetuses assume an upside-down position known as the head-down position or vertex presentation. This position is ideal for a smoother labor and delivery process as it helps the baby move through the birth canal. Fetal growth has already slowed down at this stage, so option C is incorrect. Option A is inaccurate as the fetus typically gains weight in the final weeks. Option D is incorrect because the fetus relies on the mother's immune system while in the womb.

Correct Answer: D

Rationale: Dr. Rizvi's approach to development, involving studying the relationship between changes in the brain and cognitive processing and behavior patterns, aligns with developmental cognitive neuroscience. This field combines research from various disciplines to understand how brain development influences cognitive processes and behaviors. Choice A, behaviorism, focuses on observable behaviors influenced by external stimuli. Choice B, cognitive-development theory, emphasizes cognitive growth stages. Choice C, the information-processing approach, centers on how individuals perceive, store, and retrieve information.

Correct Answer: A

Rationale: The limitation of the ethnographic method is that investigators' cultural values sometimes lead them to misinterpret what they see. This can introduce bias into the observations and potentially impact the accuracy of the findings. It is important for researchers to be aware of their own biases and strive to minimize their influence when conducting ethnographic studies. Choice B is incorrect because ethnographic methods actually aim to provide rich information on how individuals behave within their cultural contexts. Choice C is incorrect as ethnographic methods typically involve direct observation and participation rather than unobtrusive techniques like surveillance cameras. Choice D is incorrect because one of the strengths of ethnographic research is its ability to uncover the reasoning behind participants' responses by immersing the researcher in the cultural setting.

Correct Answer: A

Rationale: The corrected statement 'Paul learned to play the violin at a young age' provides an example of an age-graded influence. This is because learning to play the violin is a behavior that is typical or expected at a certain age, reflecting how age influences individuals' experiences and development. In contrast, choices B, C, and D do not directly relate to age-graded influences. Jack's enjoyment of hiking, Sarah's preference for reading mystery novels, and Alex's proficiency in mathematics are not inherently tied to age-related developmental influences.