Correct Answer: C

Rationale: The correct answer is C: embryo. The most rapid prenatal changes occur during the embryo stage, which spans from approximately 2 to 8 weeks after conception. This period is crucial as major organs and systems of the body develop rapidly, laying the foundation for future growth and development. The zygote stage is the initial single-celled entity formed by the union of sperm and egg, while the blastocyst stage involves the cluster of cells resulting from the zygote dividing and growing. The fetus stage follows the embryo stage and focuses on refining and growing existing structures rather than rapid development. Therefore, the embryo stage is where the most significant and rapid changes take place in prenatal development.

Correct Answer: C

Rationale: Max, age 65, learning to play the piano at a local senior center demonstrates that development is plastic at all ages. This means that individuals have the potential to learn and grow regardless of their age, showing that it is never too late to acquire new skills and experiences. Choice A is incorrect because it presents a negative view of aging, which is not supported by Max's actions. Choice B is incorrect as it implies that learning is restricted to certain age periods, which is contradicted by Max's experience. Choice D is incorrect because Max's learning of the piano at 65 suggests that musical talent can be developed at any age, not necessarily peaking in late adulthood.

Correct Answer: A

Rationale: Recent evidence suggests that paternal alcohol use around the time of conception can alter gene expression. This means that paternal alcohol consumption can potentially impact the genes and genetic materials passed on to offspring, affecting their development and health. Choice B is incorrect because fetal alcohol syndrome is typically associated with maternal alcohol consumption during pregnancy, not paternal alcohol use around conception. Choice C is incorrect as there is no direct link between paternal alcohol use and blood vessel abnormalities. Choice D is incorrect as paternal alcohol use can indeed have negative effects on the developing organism, particularly through altering gene expression.

Correct Answer: D

Rationale: In the eighth month of pregnancy, lanugo typically is shed. Lanugo is the fine, downy hair that covers a fetus's body to help regulate body temperature while in the womb. By the eighth month, many fetuses shed this hair as they prepare for birth. Choices A, B, and C are incorrect because fetal growth doubling, neuron production increasing, and the formation of eyes, ears, nose, jaw, and neck occur in earlier stages of pregnancy, not specifically in the eighth month.

Correct Answer: B

Rationale: By the end of Greta's first month of pregnancy, her embryo is about ¼ inch long. During the first month of pregnancy, the embryo is in the very early stages of development, and its size is typically around ¼ inch as it continues to grow and develop in the uterus. Choices A, C, and D are incorrect because sensory abilities like sensing the world, sucking thumb, and curling toes develop later in the pregnancy as the embryo progresses through different stages of development.