He committed scientific fraud after completing his phd in a seperate instance which is the one his employer found. The University then went and validated the claim of fraud his employer found, then looked back at his phd thesis, but did not find fraud. These are presumably two separate instances of academic work and the question tricked you into assuming they were the same.

the stimulus does not clearly state that "no antibiotic that has been tested against X [etc]" we are never told how it's known that no antibiotic will be powerful enough, it is simply asserted without context that "no single antibiotic on the market now on the market is powerful enough [etc.]". you shouldn't assume it's known thanks to testing. to continue more specifically on why e is not supported, we are told that yes, inevitably resistance forms, but only after a few years. for all we know e is a novel bacteria that hasn't even been around long enough for antibiotic resistance to form via any mechanism, testing or otherwise. we just do not know enough to say the stimulus supports e. X could naturally be resistant to antibiotics, it could have developed resistance without testing but just by going around the public before it was identified, the list of possibilities is potentially endless without more information. the word testing is never even used.