Correct Answer: D

Rationale: The correct answer is D because the passage specifically states that at the nanoscale, unique properties of materials emerge, which is a key benefit of nanotechnology. Choice A talks about what scientists can do but does not directly describe the benefits mentioned in the passage. Choice B is the definition of nanotechnology and not a specific benefit. Choice C mentions the use of different colors in medical tests, which is a specific application rather than a general benefit of nanotechnology.

Correct Answer: D

Rationale: In the context provided, 'defective' means faulty, referring to the gene that causes cystic fibrosis (CF). The passage explains that CF is caused by a defective gene, resulting in the production of abnormally thick and sticky fluid. The word 'defective' suggests that the gene is not functioning correctly, leading to the symptoms associated with the disease. Therefore, 'faulty' is the correct choice. The other options, 'unusual,' 'remarkable,' and 'postponed,' do not accurately capture the meaning of 'defective' in this context and are therefore incorrect.

Correct Answer: D

Rationale: The correct analogy for the role of corrective lenses in helping aging eyes can be compared to an athlete stretching before a game. Just as stretching prepares an athlete's body to perform optimally and avoid injury during a game, corrective lenses help aging eyes adjust and focus properly due to the hardening and loss of elasticity in the eye lens. Choices A, B, and C do not align with the concept of preparing or adjusting to address a specific issue, unlike the use of corrective lenses for aging eyes.

Correct Answer: B

Rationale: The correct answer is B. The passage highlights that damage to the limbic system, specifically the amygdala, can lead to passivity and lack of aggression. This is supported by the statement that patients with trauma or damage to the amygdala exhibit a complete absence of aggression. Thus, a stroke causing severe tissue damage in the limbic system, including the amygdala, can result in persistent passivity and imperturbability. Choices A, C, and D are incorrect because they do not directly relate to damage in the limbic system, which is specifically mentioned in the passage as the cause of the described behaviors.

Correct Answer: C

Rationale: In the context of the passage, 'massive' is used to describe the size of the collision that formed the Moon, indicating something very large or huge. While 'dense' means closely compacted, 'impressive' means evoking admiration, 'huge' is the closest synonym to 'massive' in this context. 'Unavoidable' does not convey the same meaning as 'massive' in this sentence, making it incorrect.