Correct Answer: B

Rationale: The author's primary purpose is to inform readers about the crucial role of microorganisms in the immune system. The essay focuses on presenting factual information and recent discoveries regarding the impact of microbes on human health. The author aims to educate the readers on the significance of microbes in human health rather than persuade them of a particular viewpoint (Choice A), entertain them with light-hearted content (Choice C), or analyze in-depth data and findings (Choice D). The essay's emphasis on informing readers about the role of microorganisms in the immune system makes 'To inform' the correct choice.

Correct Answer: B

Rationale: Basketball is not listed as a low-impact sport in the extract provided; the others (martial arts, yoga, and weight lifting) are considered low-impact activities. The extract mentions that students can participate in low-impact sports like yoga, martial arts, and weight lifting in modern PE classes, emphasizing their benefits and the focus on general skills. Basketball, on the other hand, is not included in the list of low-impact sports mentioned in the extract, making it the correct answer. This demonstrates the importance of understanding the difference between high-impact and low-impact sports for maintaining fitness and health.

Correct Answer: C

Rationale: The passage lists important nutrients for seniors, including fiber, calcium, vitamin D, and B12, while exercise is also discussed as crucial for health. However, nitrates are not mentioned at all, making option C correct since it stands out as the only nutrient not discussed in the context of seniors' health

Correct Answer: D

Rationale: The inference is that some physicians will continue with their usual recommendations while others may become more cautious.

Correct Answer: A

Rationale: The statement that the connection between sleep and weight should be explored reflects a personal viewpoint rather than an objective fact. It indicates a belief that further research is warranted to understand this relationship better, making it an opinion and distinguishing it from the other factual statements presented in the passage.