Answer:
A formal tone
longer more complex sentences
and advanced vocabulary
Explanation:
and academic discourse is like a text book or something. So think about the textbooks we were forced to read in school. Were they boring? Yes? Well which of these is most boring to you? Formal tone, longer sentences that are hard to read with a way too high vocabulary?
Or if that doesn't make sense think about someone who sounds smart to you, what makes them sound smart?