Correct Answer: C

Rationale: During the second trimester of pregnancy, a white, cheeselike substance called vernix emerges on the skin of the developing fetus. Vernix is a protective layer that helps prevent the skin from becoming waterlogged during the time in the amniotic fluid. Choice A, lanugo, is incorrect as lanugo refers to the fine, soft hair that covers the body of a fetus. Choice B, corpus luteum, is incorrect as it is a temporary endocrine structure involved in the menstrual cycle. Choice D, chorion, is incorrect as it is one of the membranes that surround the embryo and later the fetus.

Correct Answer: B

Rationale: G. Stanley Hall is generally regarded as the founder of the child study movement. He established the first American research laboratory dedicated to child psychology and education, helping to pioneer the scientific study of child development. Choices A, C, and D are incorrect as they were not primarily associated with founding the child study movement. Charles Darwin is known for his contributions to the theory of evolution, Alfred Binet is famous for developing the first intelligence test, and Sigmund Freud is renowned for his work in psychoanalysis.

Correct Answer: D

Rationale: Epidural analgesia is the most common approach to controlling pain during labor. It involves the administration of pain medication through a catheter placed in the epidural space of the spine, providing pain relief while allowing the mother to remain alert and participate in the birthing process. It is preferred by many women due to its effectiveness in reducing labor pain. Choices A, B, and C are incorrect as they do not directly address pain management during labor. While an anesthetic and a spinal block are forms of pain relief, epidural analgesia is specifically the most common method used for pain control during labor.

Correct Answer: B

Rationale: The mother feels a natural urge to squeeze and push with her abdominal muscles during the second stage of labor. This stage occurs after the cervix is fully dilated and ends with the delivery of the baby. Choice A (first) is incorrect as the first stage is mainly characterized by the dilation of the cervix. Choice C (third) is incorrect as the third stage is the delivery of the placenta, and choice D (fourth) is incorrect as the fourth stage is the recovery period after childbirth.

Correct Answer: B

Rationale: The force of blood flowing through the umbilical cord keeps it firm. The umbilical cord is the connection between the placenta and the fetus, providing essential nutrients and oxygen to the developing baby. Blood flow through the umbilical cord helps maintain its structure and function throughout the prenatal period. Choices A, C, and D are incorrect as they do not play a role in providing nutrients and oxygen to the developing baby or in maintaining its firmness.