I'm not 100% sure, but I think that the answer is: Complex Phrasing and Technical Terms. Considering the fact that Danica is speaking to people who are familiar with her topic, which would mean that Simple Words could be lost on her audience, who do not need to be treated as if they do not understand the topic, Simple Words would not be enough to appeal to them. Short Sentences may not be enough to get her point across about the topic, so going into detail may be best. As far as Slang, I believe that the audience would best benefit from the speech if Slang was not used, instead, Complex Phrasing may be best. That is why I believe that the answer is Complex Phrasing and Simple Words. (Hope my answer isn't too long! I wanted to be short, but felt the need to explain my answer so you can see why I believe it is correct, because I did state that I'm not 100% certain it is correct... So I decided to show my train of thought. Hope it helped!)