It is C. Compound sentence. This is because it is far from simple, and even thought it might seem as a run on sentence, it is not, as run on sentences are sentences connected with a comma, yet this one is connected with a semi-colon, which is a correct way of connecting sentences.
A letter of the alphabet that’s different from the others, in form of height and how it looks. (If that’s what you meant)
I think the most strongest traits in a persuasive essay: is organization, a voice, and word choice.