We know it's not A.) because that's not what they are talking about. We know it can't be B.) because the author is not persuading us (the readers) to do anything. Between C.) and D.) the only one that makes sense is D.
Try doing something with the the third one .
You should start off by saying I will be comparing ..... and ...... Something similar between them is ..... Sonething different is ....
Present is your answer.
I hope this helped!
