Quasimodo from Your Workbook Has the Utility Function

Quasimodo from your workbook has the utility function , where x is his consumption of earplugs and m is money left over to spend on other stuff. If he has $10,000 to spend on earplugs and other stuff and if the price of earplugs rises from $50 to $70, then his net consumer's surplus

A) falls by 800.
B) falls by 2,800.
C) falls by 600.
D) increases by 400.
E) increase by 1,600.