Correct Answer: C

Rationale: The correct answer is C: Dilation and effacement of the cervix. This stage can last for hours, especially for first-time mothers, as the cervix needs to dilate and efface to allow for the baby's passage through the birth canal. Once the cervix is fully dilated and effaced, the woman can begin pushing during the second stage of labor to deliver the baby. The delivery of the baby itself is usually a shorter process compared to the time taken for the cervix to dilate and efface. Choices A, B, and D are incorrect because they represent other stages within the labor process that come after the dilation and effacement of the cervix.

Correct Answer: B

Rationale: The correct answer is B: 'In South Africa, 30 percent of all pregnant women are HIV-positive.' This statement is true as South Africa has a high prevalence of HIV among pregnant women, emphasizing the need for interventions to prevent mother-to-child transmission. Choices A, C, and D are incorrect. Choice A is inaccurate as women account for more than 50% of new HIV infections globally. Choice C is misleading as the majority of new HIV infections actually occur in sub-Saharan Africa, not just developing countries. Choice D is also incorrect as without treatment, the risk of mother-to-child transmission is higher than 30%.

Correct Answer: A

Rationale: One criticism of Freud's psychosexual theory was that it did not apply to other cultures. Freud developed his theory based on observations and cases from his clinical practice in a specific cultural context, mainly Western society. This limited cultural scope raised concerns about the generalizability and applicability of his theories to diverse cultural settings. Choice B is incorrect because Freud's theory actually emphasized the significant influence of sexual feelings on human development. Choice C is incorrect because Freud's theory focused on stages of psychosexual development rather than comparing human development to the evolution of the human species. Choice D is incorrect because Freud's psychosexual theory considered environmental influences, although it primarily centered on internal drives and conflicts.

Correct Answer: B

Rationale: The correct answer is the third month of pregnancy (choice B). During the third month of pregnancy, which is around 9-12 weeks, a fetal heartbeat can typically be heard using a stethoscope. This is an exciting milestone for expectant parents as it provides reassurance about the baby's well-being. Choices A, C, and D are incorrect because by the fourth week of pregnancy, the fetal heartbeat is not usually detectable with a stethoscope. The end of the second trimester and the beginning of the third trimester are too late in the pregnancy timeline for this milestone.

Correct Answer: B

Rationale: By using random assignment of participants to treatment conditions, investigators increase the chances that participants' characteristics will be equally distributed across treatment groups. Random assignment helps reduce the likelihood of bias in the selection process and ensures that any differences between groups are due to the treatment and not pre-existing group differences. Sequential, systematic, and correlational assignment methods do not provide the same level of assurance in distributing participants' characteristics equally across treatment groups.