Correct Answer: B

Rationale: The correct answer is B: competitive athletes. Competitive athletes are often studied by researchers to investigate the impact of biological aging on motor skills because their performance is closely linked to physical abilities. Sedentary adults (choice A) may not provide a clear understanding of the relationship between biological aging and motor skills as they may not engage in consistent physical activity. Men in their mid- to late thirties (choice C) and women in their childbearing years (choice D) may not represent a group where motor skills are as finely tuned and critical to performance as in competitive athletes.

Correct Answer: B

Rationale: The correct answer is B. Fraternal twins are no more alike than ordinary siblings because they share about 50% of their genes, just like other siblings. Choice A is incorrect as fraternal twins are not genetically identical. Choice C is incorrect as fraternal twins are actually the most common type of multiple offspring. Choice D is incorrect as the likelihood of fraternal twins is not affected by the number of births a mother has had.

Correct Answer: B

Rationale: According to Erikson's theory of psychosocial development, the major personality attainment of adolescence is identity. During adolescence, individuals go through a stage called 'Identity vs. Role Confusion,' where they explore different roles and develop a sense of self. Trust (choice A) is associated with the first stage of Erikson's theory, autonomy (choice C) is linked to the toddler stage, and intimacy (choice D) is a key aspect of the young adulthood stage.

Correct Answer: C

Rationale: Dr. Kostel's belief in stage-based development aligns with the discontinuous perspective, which sees development as a series of distinct stages. The continuous perspective (choice B) suggests development as a smooth and gradual process without distinct stages. The nature perspective (choice D) focuses on genetic and hereditary influences on development. The nurture perspective (choice A) emphasizes the impact of environment and upbringing on development, which is not directly related to the belief in stage-based development.

Correct Answer: C

Rationale: The correct answer is C: 'self-indulgence'. Stagnation in Erikson's midlife stage refers to a lack of growth and self-indulgence, leading to a feeling of unproductiveness. This contrasts with 'role confusion' (A), which is associated with Erikson's adolescence stage, 'selflessness' (B) which is a positive trait, and 'guilt and shame' (D) which are emotions typically associated with earlier stages of development.