Correct Answer: B

Rationale: The passage discusses the revision of the food pyramid specifically to address the unique dietary needs of seniors. It emphasizes how the changes were made based on ongoing research and analysis, indicating a broader focus on senior nutrition rather than just individual nutrients or exercise. Thus, option B captures the essence of the passage as it succinctly summarizes the main idea.

Correct Answer: C

Rationale: The correct answer is C. The passage emphasizes the importance of certain bacteria for a properly functioning immune system. It discusses how harmless bacteria play a crucial role in defending the body against pathogens. Choice A is incorrect as it focuses on the immune system's response to certain types of bacteria in lower organisms, not the overall importance of bacteria for immunity. Choice B is incorrect as it mainly discusses bacteriotherapy in relation to the reconstruction of a damaged colon, rather than the broader role of bacteria in immune system health. Choice D is incorrect as it only talks about the process of replacing harmful bacteria with harmless ones, missing the key point about the necessity of certain bacteria for immune system function.

Correct Answer: B

Rationale: The correct answer is B. The reader can infer that the 'sweatiest students' have worked harder during class. This inference is supported by the context that students are graded based on the effort they make in the class, with some even receiving extra credit for being the sweatiest students in the room. Choice A is incorrect as there is no indication in the passage that the sweatiest students are more physically active than others; they are recognized for their effort, not necessarily for being the most active. Choice C is incorrect as the passage does not discuss the academic performance of the sweatiest students. Choice D is incorrect as there is no evidence to suggest that the sweatiest students excel in all sports activities; they are acknowledged for their effort rather than their overall sports performance.

Correct Answer: B

Rationale: The correct answer is B because the passage does not detail that mice and humans respond to microbes differently. The passage discusses how laboratory mice required a particular strain of bacteria to help their immune systems function correctly, indicating a difference in how mice and humans respond to microbes. Choices A, C, and D are all details mentioned in the passage: A discusses babies being coated with germs from the birth canal, C talks about the variation in microbes among individuals, and D states that human bodies contain more microbes than cells.

Correct Answer: D

Rationale: The study suggests that acupuncture is a reasonable treatment choice for cramps.