When __________, newborn Takeo's toes should fan out and curl as his foot twists in.

Correct Answer: D

Rationale: The correct answer is D because the description of the twisting and fanning out of newborn Takeo's toes suggests the Babinski reflex, which is typically elicited by stroking the sole of the foot from toe to heel. The Babinski reflex is a normal response in newborns and indicates proper neurological development. Choices A, B, and C are incorrect as they do not elicit the specific response described in the question.

Correct Answer: C

Rationale: Young infants usually cry because of physical needs such as hunger, discomfort, or needing to be changed. It is their way of communicating these needs to their caregivers as they are unable to do so in any other way. Choice A is incorrect because infants cry primarily to communicate physical needs, not because they are bored. Choice B is incorrect because the tone of the cry is not the reason why infants cry. Choice D is incorrect because infants cry for various physical needs, not necessarily all night long.

Correct Answer: B

Rationale: Newborn Mariana, who reacts strongly to unpleasant stimuli, is described as susceptible to colic. Colic is often characterized by excessive crying and fussiness in newborn babies, which can be challenging to console. This description suggests that Mariana's strong reactions to unpleasant stimuli may make her more prone to colic. Choices A, C, and D are incorrect because the strong reactions to unpleasant stimuli do not imply being easy to console, affect REM sleep, or responsiveness to swaddling.

Correct Answer: B

Rationale: The sense of smell in mammals, including humans, plays a crucial role in helping mothers and babies identify each other. This is important for initiating bonding and caregiving behaviors. Choice A is incorrect because the sense of smell is functional at birth and not entirely underdeveloped for several years. Choice C is incorrect as the sense of smell is actually well-developed at birth. Choice D is incorrect because the sense of smell is functional from birth and does not take several months to become adultlike.

Correct Answer: D

Rationale: Dr. Langley's work being focused on understanding constancy and change throughout the lifespan aligns with the field of developmental science, which studies how individuals grow and change from birth through old age. This field encompasses the study of physical, cognitive, social, emotional, and other aspects of development across the lifespan. Choice A, genetics, primarily focuses on the study of genes, heredity, and genetic variation, which is not directly related to understanding constancy and change throughout the lifespan. Choice B, clinical psychology, concentrates on the diagnosis and treatment of mental, emotional, and behavioral disorders rather than the broader study of development across the lifespan. Choice C, adolescent development, is more specific and limited in scope compared to the comprehensive study of development across the entire lifespan, which is the focus of developmental science.