Correct Answer: A

Rationale: Brain growth is especially dramatic during the first year of life when the brain more than doubles in size. This period is characterized by rapid neural development and growth. The brain doesn't double in size during the second year, making choice B incorrect. Middle childhood and adolescence do not represent periods where the brain more than doubles in size, making choices C and D incorrect, respectively.

Correct Answer: C

Rationale: Free radicals may contribute to oxidative stress, increasing the risk of conditions associated with a high-fat diet. When consuming a high-fat diet, the body may produce more free radicals, leading to oxidative damage. Sex hormones, over-the-counter medications, and low body weight do not directly heighten the effects of a high-fat diet like free radicals do.

Correct Answer: A

Rationale: The correct answer is A: 'any environmental agent that causes damage during the prenatal period.' A teratogen is any substance or factor that can cause harm to the developing fetus during pregnancy. Choice B is incorrect because it describes a critical period, not a teratogen. Choice C is incorrect as it refers to a specific period of development, not a teratogen. Choice D is incorrect because it describes a synthetic hormone, not a teratogen.

Correct Answer: A

Rationale: Brain growth is especially dramatic during the first year of life when the brain more than doubles in size. This period is characterized by rapid neural development and growth. The brain doesn't double in size during the second year, making choice B incorrect. Middle childhood and adolescence do not represent periods where the brain more than doubles in size, making choices C and D incorrect, respectively.

Correct Answer: A

Rationale: The correct answer is A: fluid. Fluid intelligence, which involves problem-solving and reasoning, tends to decline earlier than crystallized intelligence. Crystallized intelligence, on the other hand, involves knowledge and skills acquired over time and is more stable with age. Emotional intelligence and cultural intelligence are not directly related to the decline of mental abilities mentioned in the question, making them incorrect choices.