Correct Answer: B

Rationale: The outermost level of Bronfenbrenner's model is the macrosystem. This level refers to the broader cultural context that shapes the values, laws, customs, and resources of a particular society. It includes factors such as ideology, political systems, societal norms, and cultural influences that impact development at all other levels within the model. Choice A, microsystem, refers to the immediate environment or setting in which an individual lives and interacts. Choice C, exosystem, involves settings that individuals do not directly experience but still influence them. Choice D, mesosystem, refers to the connections between various aspects of an individual's microsystem.

Correct Answer: B

Rationale: During the first week of pregnancy, the zygote (fertilized egg) undergoes rapid cell divisions and forms a blastocyst. This is a crucial stage where the cells differentiate and specialize, setting the foundation for the development of the embryo. It is during this time that the zygote implants itself into the uterine wall, initiating the process of pregnancy. Choices A, C, and D are incorrect because during the first week of pregnancy, the focus is on the initial development and multiplication of the zygote, not on the development of heart muscles, a primitive brain and spinal cord, or the embryo's ability to move.

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.

Correct Answer: C

Rationale: The second leading cause of neonatal mortality in the United States is low birth weight, which is largely preventable through proper prenatal care, nutrition, and health interventions. Low birth weight infants are at higher risk for various health complications and mortality, making it an important issue to address in maternal and child health programs. Malnutrition (choice A) can contribute to low birth weight but is not the direct cause of neonatal mortality. Physical abnormality (choice B) can be a factor in some cases but is not the second leading cause overall. Sudden infant death syndrome (choice D) refers to unexplained deaths of seemingly healthy babies and is not related to low birth weight as a leading cause of neonatal mortality.

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.