The amount on hand I believe. You are accounting for how much was used during the accounting period and it would show up on the adjusted trial balance, not the regular one.
C, the amount on hand
thx for the points btch... ( being sarcastic, nobody got the points)
This depends on the adjustment.
If you are debiting prepaid rent (+Asset) then this would indicate the amount of prepaid rent bought.
If you are crediting prepaid rent (-Asset) then this would indicate the amount of prepaid rent already used (expired).
Judging by this question and the lack of information, I would say the answer is (A), the amount bought.