__________ increases tenfold from the twentieth week until birth.

Correct Answer: B

Rationale: Brain weight increases tenfold from the twentieth week until birth. This rapid growth and development of the brain during the prenatal period is crucial for setting the foundation for future cognitive and neurological functions. Choices A, C, and D are incorrect because although they also undergo changes during prenatal development, none of them increase tenfold from the twentieth week until birth, unlike brain weight.

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: The best-known effect of smoking during the prenatal period is low birth weight. Smoking during pregnancy is a known teratogen that can lead to negative outcomes for the developing fetus, such as growth restrictions resulting in low birth weight. This condition can have significant long-term consequences on the child's health and development. Choices A, B, and D are incorrect as they are not the primary effect associated with smoking during the prenatal period. Colic is typically associated with digestive issues, respiratory distress at birth can be caused by various factors other than smoking, and delayed language development is not directly linked to smoking during pregnancy.

Correct Answer: C

Rationale: The correct answer is C: 'poorer the child's achievement scores in the school years.' Prenatal exposure to alcohol has been linked to a range of cognitive and behavioral difficulties, including lower academic achievement in children. These difficulties may manifest as poor achievement scores in later school years. Choices A, B, and D are incorrect because alcohol consumption during pregnancy is not associated with higher birth weight of the child, the likelihood of ARND instead of FAS or p-FAS, or greater speed of information processing in the child.

Correct Answer: A

Rationale: Men with even tiny amounts of dioxin in their bloodstream father nearly twice as many girls as boys. This is due to the impact of dioxin exposure on sperm cells, leading to a skewed ratio of female to male offspring. Choice B is incorrect as the question specifically mentions that men father more girls than boys. Choice C is incorrect as dioxin exposure does not necessarily lead to more twins and triplets. Choice D is incorrect as men with dioxin in their bloodstream father more girls, not fewer children overall.