An example of the speaker not considering his audience and using unfamiliar slang is: D. B and C.
Slang is known to be a kind of language that makes use of informal words which are commonly used in speech than in writing and a usually restricted to a set of people. Use of slang shows familiarity among the people.
Option D actually points to B and C. In options B and C we see that the audience's reaction shows that they were unfamiliar with the slang and also uninterested with what Susan was saying.
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