Straight C here.
1. Tells us what the balance would have been at a 12% increase, but nothing more
2. Tells us what percent the account increased by, but not where it started
a = account balance at beginning of month
b = account balance at end of month
1.12a = 504
1.08a = b
1.12a/1.12 = 504/1.12
a = 450
1.08(450) = 486
account balance on May 30 was $486
I have the same answer but the OA is A. which is silly!