Correct Answer: D

Rationale: The male produces sperm in the testes, which are two glands located in the scrotum. The scrotum is the external sac that houses and protects the testes, allowing for optimal temperature regulation to support sperm production. Choice A is incorrect because sperm production does not occur in the penis. Choice B is incorrect because the scrotum houses the testes, not the penis. Choice C is incorrect because sperm is produced in the testes, not the penis.

Correct Answer: B

Rationale: In an experiment, the independent variable is the one that the investigator expects to cause changes in another variable. It is the factor that is deliberately manipulated or changed by the researcher to observe its effects on the dependent variable. The purpose of manipulating the independent variable is to study its impact on the outcome, allowing researchers to establish cause-and-effect relationships in their investigations. Choice A is incorrect because the independent variable is not influenced but rather influences another variable. Choice C is incorrect as the independent variable is intentionally manipulated by the researcher. Choice D is incorrect as it refers to a different concept unrelated to the independent variable in an experiment.

Correct Answer: C

Rationale: During the third stage of labor, the correct answer is C, the placenta is delivered. This stage occurs after the baby is born and involves the expulsion of the placenta from the uterus. Choice A is incorrect because the thinning of the cervix to nothing typically occurs during the first stage of labor. Choice B is incorrect as uterine contractions usually begin during the first stage of labor to help with the dilation of the cervix. Choice D is incorrect because the baby is typically born in the second stage of labor, not the third.

Correct Answer: D

Rationale: Lanugo helps the vernix stick to the skin. Vernix is a waxy substance that covers the fetus's skin during pregnancy. Lanugo is a fine, downy hair that helps to anchor the vernix to the skin, providing protection and nourishment to the developing fetus. Choices A, B, and C are incorrect as they do not accurately describe the role of lanugo in prenatal development.

Correct Answer: A

Rationale: Sigmund Freud constructed his psychosexual theory on the basis of his adult patients' memories of painful childhood events. Freud believed that events in early childhood had a significant impact on an individual's development and personality. He used his patients' recollections of childhood experiences to develop his theories on psychosexual development. Choice B is incorrect as Freud did not base his theory on studies of animal behavior. Choice C is incorrect as Freud's theory was not solely based on interviews with institutionalized children and adolescents. Choice D is incorrect as Freud did not construct his theory by observing his own children.