Correct Answer: B

Rationale: The study outlined in the passage indicates that children who lack adequate sleep are at a higher risk for behavioral and physical issues, such as obesity and attention disorders. This conclusion is derived from the evidence provided in the passage, suggesting a direct link between sleep deprivation and negative outcomes, thus supporting option B..

Correct Answer: C

Rationale: The correct answer is C: 'Found everywhere.' Ubiquitous in this context means widespread presence. In the provided extract, it is mentioned that MRSA bacteria have become ubiquitous not only in hospitals but also in various other settings, indicating they are found everywhere. Choice A, 'Indigenous,' is incorrect as it refers to something native or originating from a specific place, which is not the intended meaning in the context. Choice B, 'Often ignored,' is incorrect as ubiquitous means something that is widely present, not something that is ignored. Choice D, 'Dangerous,' is incorrect as ubiquitous does not directly imply danger, but rather the widespread presence of something.

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 inference that can be made is that medical mistakes can happen even at the best hospitals.

Correct Answer: C

Rationale: The tone of the essay is discouraged as it expresses concern about the U.S.'s lower life expectancy ranking and contributing factors.