A research paper is fact and nothing but the fact. A research paper is just giving information about a topic. However, rhetorical questions are used to persuade the reader to believe or agree with something, mainly in a discursive essay; but in a research paper, you aren't persuading, you are educating.
I would say that the answer is probably 3. Hope this helped!
-TTL
for the first you would put way
for the sending you would but Leno
and for the third you would put job ,
