Which of the following statements is true in a situation where a consumer would decrease their total utility by buying more oranges than apples?

a.The marginal utility per dollar spent on oranges must be less than that of apples.

b.The marginal utility of oranges must be higher than that for apples.

c.The marginal per- unit cost of apples must be more than the marginal per- unit cost of oranges.

d.The marginal utility per dollar spent on oranges and apples must be the same.