Terrence claims that a new species of bacteria should be placed on the list of bacteria that cause infectious diseases. He ran his experiment several times in one day and got the same results. Ben and Frieda also ran his experiment multiple times themselves. They never got the same results that Terrence did.

A scientific claim should be reproducible: other people should be able to repeat the experiment and get similar results. Terrence repeated it himself, but Ben and Frieda could not reproduce his results, so the claim has not stood up to independent experimentation. Therefore, choice A is correct; repeating the experiment only once with the same person, as in choice C, is not enough to establish the claim.

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