It is difficult to isolate the precise damage caused by illegal drugs during pregnancy because __________.

Correct Answer: D

Rationale: The difficulty in isolating the precise damage caused by illegal drugs during pregnancy is due to the fact that drug users often take several drugs, display other high-risk behaviors, and suffer from other stresses. This makes it challenging to identify the specific impact of each individual factor on prenatal development. Choices A, B, and C are incorrect because they do not address the complexity of the situation involving drug users during pregnancy. Most drug-using mothers refusing to participate in teratology research, the majority of babies not surviving, or drug-using mothers quitting during the first trimester do not directly explain the difficulty in isolating the precise damage caused by illegal drugs during pregnancy.

Correct Answer: A

Rationale: Pregnant women are wise to avoid eating long-lived predatory fish, which are heavily contaminated with mercury. Mercury is a known teratogen, meaning it can negatively impact the development of the fetus and lead to birth defects. It is recommended that pregnant women choose fish with lower levels of mercury to reduce potential risks to the baby's health. Choices B, C, and D are incorrect because lead, polychlorinated biphenyls, and radiation are not typically found in fish at levels that pose significant risks to pregnant women and the developing fetus.

Correct Answer: C

Rationale: To avoid exposure to toxoplasmosis, Kaye should ask other family members to change the litter box. Toxoplasmosis is a parasitic infection that can be transmitted through cat feces, so it is important for pregnant women to avoid handling cat litter to reduce the risk of infection. Choices A, B, and D are incorrect because they are not directly related to preventing toxoplasmosis. Smoking cessation is important for overall health but not specifically to prevent toxoplasmosis. Picking up after the dog and feeding the fish are not relevant to preventing toxoplasmosis, as the infection is primarily associated with cat feces.

Correct Answer: B

Rationale: Folic acid supplementation early in pregnancy is crucial as it reduces the risk of abnormalities in the developing fetus. It is specifically known to prevent issues related to the neural tube, circulatory system, and urinary tract. Vitamin A, Vitamin D, and Vitamin C do not play the same role as folic acid in preventing these specific birth defects, making them incorrect choices.

Correct Answer: D

Rationale: Adolescent children of mothers who were home-visited as part of the Nurse-Family Partnership reported less alcohol and drug use compared to their comparison-group agemates. This indicates that the program may have a positive impact in reducing risky behaviors among adolescents whose mothers received home visits. Choices A, B, and C are incorrect because the extract specifically mentions that the children reported less alcohol and drug use, and there is no mention of impulsivity, overactivity, academic achievement scores, or aggressive behavior in this context.