[Q]: Mike is a physician who treats HIV-infected patients. Today, he is seeing two patients, patient A and patient B. Patient A is infected with HIV, but patient B is not infected with HIV. Mike is trying to figure out how HIV-infected patient is different from the patient who is not infected with HIV. Which patient would have less T cells, patient A or patient B?
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[A]: patient A

[Q]: Bob and Andy were two nature enthusiasts. They went camping together once a month. Bob was into bird watching, while Andy was fascinated with frogs and salamanders. They went on a trip last week-end and they were very happy with what they had observed. Which friend heard more frog calls during the day?
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[A]: Andy

[Q]: The students studied two ponds. Class A studied a pond filled with protozoa, while class B studied a pond with almost no protozoa. Which class observed fewer herbivore protozoa?
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[A]: class B

[Q]: Bob works as a scientist for a large fishing company in Norway. Norway's government has strict regulations on fishing to protect its fish stock. Part of Bob's job is to provide the government with fish mortality data. Today, he has two samples of fish to investigate, sample A and sample B. Bob concluded sample A had natural mortality, but sample B had fishing mortality. For which sample predation would not be a cause of death, sample A or sample B?
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[A]:
sample B