A. building tables,
because I'm not sure how that will exactly help you in studying. However, in my opinion, the other three seem able to work.
Sorry if this answer is kind of late, but this is the first time in ages since I've logged on. Have a good night and life though! :3
I blame you (with a passive voice)
no, I don't believe in stories invented by high sheepherders thousands of years ago..