Correct Answer: C

Rationale: In field experiments, researchers randomly assign participants to treatment conditions in natural settings. This method allows for a higher level of control over potential confounding variables compared to non-random assignment. Random assignment helps ensure that the groups being compared are comparable at the beginning of the study, which strengthens the internal validity of the research findings. Choice A is incorrect because selective assignment may introduce bias. Choice B is incorrect as researchers can use random assignment in field experiments. Choice D is incorrect because field experiments typically have less control over the treatment compared to laboratory experiments.

Correct Answer: B

Rationale: G. Stanley Hall and his student, Arnold Gesell, launched the normative approach. This approach involves studying large numbers of people of different ages and examining the age-related averages of behaviors to establish norms or typical development patterns. These scholars focused on the systematic observation of how and when certain behaviors appear in children. Choices A, C, and D are incorrect because they do not accurately reflect the contributions of G. Stanley Hall and Arnold Gesell in the field of developmental psychology.

Correct Answer: A

Rationale: In the germinal period of prenatal development, which lasts for about the first two weeks after fertilization, the developing organism is a zygote that has not yet implanted in the uterus. During this period, teratogens rarely have any impact because essential implantation and early cellular division processes are occurring. Teratogens are more likely to have significant effects during the later embryonic and fetal periods of development. Therefore, the correct answer is A. Choice B, embryonic period, is incorrect because teratogens have a higher likelihood of impacting development during this period. Choice C, fetal period, is also incorrect as teratogens can impact development during this stage as well. Choice D, prenatal, is a broad term encompassing the entire period of development from conception to birth and is not a specific developmental stage where teratogens have a minimal impact.

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: In field experiments, researchers randomly assign participants to treatment conditions in natural settings. This method allows for a higher level of control over potential confounding variables compared to non-random assignment. Random assignment helps ensure that the groups being compared are comparable at the beginning of the study, which strengthens the internal validity of the research findings. Choice A is incorrect because selective assignment may introduce bias. Choice B is incorrect as researchers can use random assignment in field experiments. Choice D is incorrect because field experiments typically have less control over the treatment compared to laboratory experiments.