Artist's Block

I've got a case of artist's block going on right now. I just started a maymester class today and it has given me a great dilemma. I have to made 8 individual prints in 12 days. In the last print class I took the professor was not a big fan of the images I chose to make. Actually he critiqued everything that I was meaning to do through my work. In this print class, I have the same prof, and he will approve or disapprove me from being able to actually go on in my major this summer.  So in this class, I decided to go another way with my work, in order to impress my prof, and therefore get a good grade. So in class I was today sketching some and came up with a very intriguing idea to explore. I showed it to my prof, but he didn't like it because the two images were too different and seemed like two separate ideas. So he suggested that I go with one idea and run further with it. 

So I really have been trying to do that, but I'm stuck. I'm really excited about the idea that I came up with today, and I can't seem to come up with anything else I like. I have been looking through photos, sketches, old drawing, paintings, and even looking through the house to find something I'm interested in to print. But I have come up empty handed. 

Now here's the question. Do I go with the idea that I am really interested in or the one that my prof likes? If I go with the one that I'm really interested in then I'll make a great print. If I go with the one that my prof likes, then i'll get a good grade. Should I be true to myself as an artist? Or should I do what will get me out of school?