Correct Answer: C

Rationale: The correct answer is C. The passage aims to provide an overview of cystic fibrosis (CF) and how it is inherited. It explains that CF is passed down through families due to a defective gene, detailing how this gene affects the body and who is most commonly affected by the disease. Choices A, B, and D are incorrect because the passage does not solely focus on describing the causes of CF, explaining how it is passed down through families, or reviewing why some Americans have CF while others do not. Instead, it provides a broader perspective on CF and its inheritance.

Correct Answer: B

Rationale: Macmillan added iron rims to his bicycle tires to enhance their durability and make them last longer. This innovation aimed to prevent the tires from getting worn down quickly. Adding weight to the bicycle (Choice A) was not the purpose of adding iron rims. While adding iron rims could potentially reduce the bumpiness of the ride (Choice C) by providing more stability, the main objective was to improve tire longevity. Similarly, reducing the level of fatigue during the ride (Choice D) was not the primary reason for adding iron rims.

Correct Answer: C

Rationale: The mention of impact craters in the text is to highlight the consequence of the Moon lacking an atmosphere. The absence of an atmosphere on the Moon leaves it vulnerable to meteorite impacts, resulting in the multitude of impact craters on its surface. Choice A is incorrect because the mention of impact craters is not related to atmospheric weathering but rather to the lack of an atmosphere. Choice B is incorrect as it misinterprets the reason for the absence of plant life on the Moon. Choice D is incorrect as the text explicitly states that the Moon lacks tectonic or volcanic activity, which is not the focus of the mention of impact craters.

Correct Answer: C

Rationale: The correct answer is C. The paragraph is biased against people with piercing or harsh voices, suggesting they are less desirable as public speakers, newscasters, or political candidates. The text explicitly mentions that harsh voice qualities, like being shrill, grating, hard, piercing, brassy, loud, or nasal, are undesirable and may make people uncomfortable when speaking. It also highlights that tension leading to harsh voice qualities is more common in higher-pitched voices, which are typically associated with women, making them less preferred for public speaking roles. Choices A, B, and D are incorrect because the text does not suggest a balanced view, favor low-pitched voices, or maintain neutrality towards both high- and low-pitched voices; instead, it emphasizes the negative impact of harsh and piercing voices.

Correct Answer: B

Rationale: The best title for this passage would be 'A ride through the history of bicycles' as it provides a comprehensive overview of the historical development of bicycles from their invention to modern times. Choice A, 'Bicycles are better,' is incorrect as it does not capture the essence of the passage, which focuses on the history and evolution of bicycles rather than their superiority. Choice C, 'Cycle your way to fitness,' is misleading as the passage does not primarily discuss the fitness aspect of cycling but instead focuses on the evolution of bicycle design. Choice D, 'The popularity of bicycles,' is too narrow as it only touches on one aspect mentioned briefly in the passage, while the passage covers a broader historical perspective.