Informal language would be the answer.
We can eliminate a, because a formal language would be serious, and not have a humorous tone.
Parallel structure is the repeating of phrases in a text. This is not used to produce humor but to drive the point home to the reader or listener.
Chronological order is saying the events in the order the happened, and thus doesn't really have anything to do with a humorous tone.
Hope this helps!
