GWD数学题请教

melody远行

From May 1 to May 30 in the same year, the balance in a checking account increased. What was the balance in the checking account on May 30?

(1)If, during this period of time, the increase in the balance in the checking account had been 12 percent, then the balance in the account on May 30 would have been $504

(2)During this period of time, the increase in the balance in the checking account was 8 percent.

这题给的答案是A，可是我觉着应该选C，因为第一个条件说的是如果是12%，可是我们不知道到底是几。
这题给的答案是A，可是我觉着应该选C，因为第一个条件说的是如果是12%，可是我们不知道到底是几。

melody远行

有会的同学能教教吗？