Answer:
10) Is A, "double entry bookkeeping", because if it were single entry, I'd imagine there'd only be one side to record, therefore you wouldn't have a right side or a left side.
11) Is A, "debits", they are generally recorded on the left side.
12) Is B, "credits", they are generally recorded on the right side.
Does this make sense? If it doesn't, then I'm sincerely sorry, but I don't really know how to explain it.