We really dont know much about the paragraph but i have read this beforen. the answer is A
I would imagine "a comfortable amount of eye contact" would be a sign that you are confident, so that can be crossed out of the list.
"Business attire" gives off a professional vibe, which means if you happen to wear business attire, you're most likely serious about your topic and are confident about it, so that's also false.
Slouching could mean that you are not confident. When talking, you should stand straight up, slouching could give your audience the impression that you weren't well prepared for your topic or you're not confident about it.
So your answer should be "slouching" :)
Parallel structure means using the same pattern of words to show that at least two ideas are equally important as each other. Parallel structure can be used to create a rythem or a pattern in certain types of sentences.
