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.

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: C

Rationale: The main idea of the passage is that innovations and improvements in bicycle design have made bicycles one of the most popular means of recreation and transportation worldwide. The passage outlines the evolution of bicycles from their early designs to the modern versions, emphasizing how these changes have contributed to their popularity. Choice A is incorrect because it focuses only on the current status of bicycles, while the main idea encompasses the evolution and improvements in design. Choice B is incorrect as it mentions the invention of the first modern bicycle but does not address the overall impact of innovations on bicycle popularity. Choice D is incorrect as it simply states a fact without capturing the essence of the passage, which is about the impact of design improvements.

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: 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.