Hi Sarah,
This sort of depends on what writing we're talking about. If you are doing any kind of scientific or research-based writing, figures and graphs are certainly acceptable. If you're writing a short story, though, maybe not so much. But, in general, I'd say the answer is probably C. The answer would be more obvious if it said "not using abbreviations where appropriate," but I think we can assume that's what it means. Grammar rules (specially forms like APA) do often require that some words be abbreviated once introduced. Commonly abbreviated words are ones like FBI, RSVP, or any lengthy names of organizations or titles that have already been introduced (so, if you were writing a piece about a school, like, say, New York University, you'd be expected to introduce the abbreviation of "NYU" and use that going forward).
Let me know if that makes sense and if you have any other questions!