Suppose That Fiona Spends All of Her Income on 10

Suppose that Fiona spends all of her income on 10 units of good X and 14 units of good Y. Fiona's marginal utility from the 10ᵗʰ unit of good X is 24 utils, and her marginal utility from the 14ᵗʰ unit of good Y is 20 utils. If the price of good X is $8 per unit and the price of good Y is $5 per unit, then to comply with the rational spending rule, Fiona should:

A) purchase more than 10 units of good X and less than 14 units of Y.
B) purchase less than 10 units of good X and more than 14 units of good Y.
C) purchase more than 10 units of good X and more than 14 units of good Y.
D) continue to purchase 10 units of good X and 14 units of good Y.