Correct Answer: D

Rationale: The formal operational stage in Piaget's theory is characterized by abstract reasoning, hypothetical thinking, and logical reasoning. This stage represents the most complex period of cognitive development according to Piaget. Choices A, B, and C refer to earlier stages in Piaget's theory and do not involve the level of abstract thinking and logical reasoning seen in the formal operational stage.

Correct Answer: D

Rationale: The formal operational stage in Piaget's theory is characterized by abstract reasoning, hypothetical thinking, and logical reasoning. This stage represents the most complex period of cognitive development according to Piaget. Choices A, B, and C refer to earlier stages in Piaget's theory and do not involve the level of abstract thinking and logical reasoning seen in the formal operational stage.

Correct Answer: C

Rationale: The correct answer is C: concrete operational. During the concrete operational stage, children start to engage in logical thinking about concrete events. This stage typically occurs between the ages of 7 to 11 years. Choices A, B, and D are incorrect. The sensorimotor stage (choice A) is the first stage in Piaget's theory, occurring from birth to about 2 years old. The preoperational stage (choice B) follows the sensorimotor stage and occurs roughly from ages 2 to 7 years. The formal operational stage (choice D) is the final stage in Piaget's theory, where abstract thinking and hypothetical reasoning develop, usually beginning around age 11.

Correct Answer: D

Rationale: The correct answer is D, antigens. Antigens are substances recognized by the immune system as foreign, triggering an immune response to neutralize or destroy them. In this context, T cells and B cells are specialized cells of the immune system that respond to antigens, but they are not the substances being neutralized or destroyed. Telomeres, on the other hand, are protective structures at the end of chromosomes and are not targeted for neutralization or destruction by the immune system.

Correct Answer: D

Rationale: According to the lifespan perspective, no single period is considered supreme in its impact on the life course. Each stage of life, from prenatal period through adulthood, plays a significant role in shaping an individual's development. Therefore, the correct answer is 'D: no age period.' Choices A, B, and C are incorrect because the lifespan perspective emphasizes that all stages are important and contribute uniquely to an individual's life course.