It isn't simile, because there is no comparison to anything, and it isn't ironic.
The answer is D Cats are the smartest animals.
I am going to say B because it seems most appropriate.
You did not provide the possible excerpts, however, nonstandard English is any type of English language that is not standardized, meaning that is not grammatical or normative. Slang, jargon, incorrect grammar, dialects, all fall into the category of nonstandard English, so use that logic on your excerpts and find the correct one.
The way the author makes the story is what actually affects all of that