Correct Answer: B

Rationale: Dr. Wu's observation of children's responses to bullying by watching them play in a park is an example of naturalistic observation. Naturalistic observation involves observing behavior in a natural setting without any manipulation or intervention. Dr. Wu is simply observing the children's behavior in a real-world setting to gain insights into how they respond to bullying, making it a naturalistic observation.

Correct Answer: B

Rationale: The two main types of designs used in all research on human behavior are correlational and experimental. Correlational research examines the relationship between two or more variables without establishing causation, while experimental research involves manipulating one variable to observe the effect on another variable. These two types of designs are fundamental in understanding and studying human behavior.

Correct Answer: B

Rationale: Stress hormones during labor and delivery actually help arouse the infant into alertness. These hormones can promote the infant's readiness to adapt to the new environment outside the womb.

Correct Answer: A

Rationale: In an experimental study, the independent variable is the factor being manipulated or controlled by the researcher. In this case, the frequency of read-alouds is the variable that researchers would intentionally change or vary to see its effect on the dependent variable, which is the children's vocabulary scores. The other options (B. type of books parents read, C. child's vocabulary score, and D. difficulty of vocabulary words) are not the independent variable in this study as they are either irrelevant or are the outcome being measured.

Correct Answer: A

Rationale: The rooting reflex is the correct answer. This reflex helps a newborn baby find the nipple by turning their head and opening their mouth when their cheek is stroked or touched. This is crucial for the baby to locate and latch onto the mother's breast for feeding. The rooting reflex typically disappears around 4 months of age.