When choosing a topic for your writing project, you should consider A. the course description of your class, because this will indicate your instructor's preference. B. the topics others in your class are writing about so that your project will be original. C. your assignment, because the length of your paper will affect how broad or narrow your topic is. D. how many different entries turn up in an online search.
I would say C. because if you are asked to write 10 pages then you aren't going to talk about what you ate last night, but a broad topic that can fill that many pages. That's how I do it in class anyways...