A student says, "Since the Zn rod becomes negatively charged, it cannot be the site of oxidation." Which option best evaluates this claim using the notes?

The claim is incorrect. The notes explain that zinc atoms leave as $Zn^{2+}$ and the electrons are left behind on the rod, so the rod becomes negatively charged. That negative charge is actually a consequence of oxidation here, not evidence against it. Option A is the strongest distractor, but the sign developed locally does not change the fact that oxidation is occurring at the zinc electrode.