If Callum Is Consuming His Utility Maximising Bundle and the Price

Multiple Choice

If Callum is consuming his utility maximising bundle and the price of one good rises, what happens to the marginal utility per dollar spent on this good (MU/P) , and what should Callum do?

A) MU/P has increased, and Callum should buy more of this good.
B) MU/P has increased, and Callum should buy less of this good.
C) MU/P has decreased, and Callum should buy more of this good.
D) MU/P has decreased, and Callum should buy less of this good.