Why is C correct? Why is D incorrect?

@Ryan-Mahabir, (D) actually strengthens the argument. If the articles are checked by more editors, and the gazette still runs significantly more corrections than its competitor, than having more editors is not actually helpful as the argument concludes. (C) is correct because it provides an alternative explanation for the fact that the gazette runs more corrections than its competitor. The higher number of corrections is explained by the fact that it actively follows up on readers' complaints rather than the implication that its editors overlook factual errors.

I am confused about this question and the correct answer... I got it right because I was able to eliminate but I still do not know how C weakens the author's argument. I mean if the readers are complaining about factual errors in the paper, that means those factual errors are being made and are not being avoided by the editors because they are not noticing them until they read readers complaints... i am just confused. Could you explain the whole thing please?

i thought E was reasonable because fewer reporters would mean more errors so the editors would miss more and lead to more corrections