Here is what I thought about this answer:
Trevalga: Submitted 30+ poems in 2 years without publication --> Publication has unfairly discriminated against poems
Publisher: Poetry editor judges all submissions without ever seeing names --> Could not have known it was Trevalga --> Process is fair
What is the assumption of the publisher?
The assumption here could be between the premise and the intermediate conclusion (could not have known it was Trevalga). The glaring issue is here is that, just because the editor cannot see names, why does it follow that the editor does not know Trevalga's work? Perhaps Trevalga uses a very particular writing style about particular subjects and the editor does not publish anything that looks like it could be his work. Either way, this is what I am looking for when going to the answers.
(A) This helps the publisher's argument but it really isn't necessary. Even if the publisher does bear a grudge, this wouldn't matter in theory because the editor supposedly doesn't know if it is the work of Trevalga. I am looking for something more concrete than this that attacks the gap.
(B) This is not really assumed by the publisher at all. However, it is assumed by Trevalga. This is a trick answer for those that misread the question.
(D) Opposite (or at least very close to it). This actually hurts the publisher's argument if we assume this. If we negate it, it helps the argument! Eliminate.
(E) Similar to (A), this might help the publisher's argument yet it is not necessary. So what if he submitted it under his pen name? This still doesn't attack the gap between no name and not knowing.
(C) Perfect! Exactly what I was looking for. If we say the negation, it looks like this: "Trevalga recognizes the poems only if his name is attached to it."