Kelly,
The stimulus is claiming that quantum physics withstood all the serious attempts so far, and answer choice (B) is referring to the past tense as well, so that's no objection to the answer. The stimulus also thinks that having the deviations within the margin of error constitutes withstanding the challenge - otherwise, the theory wouldn't have survived even challenges in the past. If we take its margin of error to indicate that there's some room for a future challenge to succeed and strike down quantum physics, that's still fine - answer choice (B) is about all the serious attempts that have happened so far.
If answer choice (B) were instead "A scientific theory should be accepted if it will survive all serious attempts to disprove it," then it would be an inadequate answer, because we don't know how it will survive future challenges.
Answer choice (E) cannot possibly help the argument. It is a conditional:
a theory should be accepted
its predictions have not been disproven by experiment
Regardless of what the necessary condition said, this answer cannot ever help the argument. Because the conclusion of the argument ("accept the theory") is in the sufficient condition of this conditional, a statement like this is saying "In order for the conclusion to be true, something else is necessary." How could that help? If the "something else" is false, then, via the contrapositive, that would weaken the argument. If the "something else" is true, then we have the necessary condition of a conditional true...which gets us nowhere. To say "If the necessary is true, then the sufficient must be true" is to make the mistake of a Mistaken Reversal.
This is a point that generalizes and is especially helpful in Strengthen questions. If the answer choice is a conditional that has the conclusion's concept as the sufficient condition, that answer cannot be helpful. If the conclusion concept is necessary, or the NEGATION of the conclusion is sufficient, then the answer may help, and we have to evaluate the details to see whether it helps. Answer choice (B), for instance, is a conditional that has the conclusion concept as its necessary condition. The sufficient condition's being true in the stimulus is why answer choice (B) is helpful, and thus the correct answer.
Robert Carroll