Correct Answer: A

Rationale: The correct answer is A: 'They regulate the development of traits.' Genes play a crucial role in regulating the development of traits by encoding proteins that control various bodily functions and characteristics. This process involves gene expression and the production of proteins that ultimately determine an individual's traits. Choice B is incorrect because genes do not have a direct role in preventing foreign particles from entering the body; this function is primarily carried out by the immune system. Choice C is incorrect as genes do not specifically work with lutein to influence development; genes operate independently to regulate trait expression. Choice D is incorrect as genes are not responsible for transferring oxygen in the bloodstream; this function is carried out by red blood cells and hemoglobin.

Correct Answer: D

Rationale: An amniocentesis in this scenario is most likely being performed to assess fetal lung maturity. This is necessary when considering early delivery due to macrosomia (large fetal size), which is a common concern in gestational diabetes. Evaluating fetal lung maturity is crucial to determine if the fetus's lungs are developed enough to support breathing independently outside the womb. The presence of a neural tube defect and chromosomal abnormalities are not typically assessed through amniocentesis in this situation, and determining the gender of the fetus is not the primary purpose of the procedure here.

Correct Answer: B

Rationale: The correct answer is B. The fetus typically begins to respond to external stimulation much later in pregnancy, usually after the first trimester. During the second or third week of pregnancy, the fetus is still in the early stages of development and is not yet capable of turning or responding to external stimuli. Choices A, C, and D are incorrect because they do not accurately reflect the timeline of fetal development when it comes to responding to external stimulation.

Correct Answer: D

Rationale: The correct answer is D because feeling quickening typically occurs around 18-20 weeks of gestation, indicating fetal movement. This is an appropriate time to auscultate the fetal heart rate. Choice A is incorrect because a molar pregnancy is not a viable pregnancy, and auscultating the fetal heart rate in this case is not applicable. Choice B is incorrect because a crown-rump length of 7 weeks gestation is too early for fetal heart rate auscultation. Choice C is incorrect because a positive urine pregnancy test alone does not indicate the appropriate timing for fetal heart rate auscultation.

Correct Answer: C

Rationale: The correct answer is Cephalhematoma. Cephalhematoma is a collection of blood between the skull bone and periosteum that does not cross the suture line. It often occurs due to birth trauma, such as forceps delivery, leading to localized swelling. Caput succedaneum (Choice A) is diffuse swelling of the scalp that may cross suture lines and is typically present at birth. Hydrocephalus (Choice B) is an abnormal accumulation of cerebrospinal fluid within the brain's ventricles. Microcephaly (Choice D) is a condition characterized by a smaller than average head size and may be present at birth or develop later in infancy.