I would say that it's best to use D, compare and contrast. In a compare and contrast writing, two subjects are being compared and contrasted. Depending on how you organize your writing, you can talk about one subject first and then the other.
You'll want to leave it out. if it isn't conducive to the content of your paper, it's more like a distraction from what you're trying to say. parentheses might be a "safe" way to signify a side topic, but it weakens the paper as a general statement because the reader has to pause and take a moment to absorb a new topic before going back to what you were saying
Clearance received his angel wings
