Which of the following topics would be suitable for a short research paper?
an in-depth study of mary shelley's frankenstein
a comparison of homer's iliad and odyssey
an analysis of edgar allan poe's narrative style in "the black cat"
an analysis of protagonists in jane austen's works
a discussion about the use of symbolism in the novel moby-d*ck (i can't believe i have to censor that.)

there can be more than one answer.

An in depth study of Mary Shelley's Frankenstein would not be a short research paper. Ideally you would have to have a more specific research question/focus on one aspect of the novel. An in depth study is too broad.

An analysis of protagonists in Jane Austen's works once again would not be a short research paper, if it was limited to one or two of her books then yes but not all of them.

A comparison of Homers Illiad and Odyssey once again is too broad a topic and if you were to compare everything in both novels you would be looking at a rather lengthy research paper.

Moby D*ck is full of symbolism and if you could find a way to summarize effectively and succinctly the story and maybe just focus on the actual whale as the subject matter and what it represents in the book you could definitely make a good relatively short research paper out of it.  

Alternatively would be an analysis of Edgar Allan Poe's narrative style in The Black Cat. The Black Cat is a short story and ideal for this type of research paper.