Nick Has $300 a Month to Spend on Either Detailing

Multiple Choice

Nick has $300 a month to spend on either detailing his sports car or buying bottles of good wine. It costs $100 to have his car detailed and a bottle of wine is $50. He currently buys four bottles of wine each month and has his car detailed once. If the price of car detailing decreases to $75, Nick's budget constraint will:

A) shift straight outward, because he is relatively wealthier.
B) rotate and change its slope, because relative prices have changed.
C) shift straight inward, because he is relatively wealthier.
D) This cannot be answered without knowing the marginal utility of each good.