When Ian experiences diminishing marginal utility when buying shirts,
a. the price of each additional shirt he purchases falls when he gets volume discounts.
b. the price of each additional shirt he purchases falls when he gets volume discounts.
c. the value of the shirt he purchased start to fall as they wear out over time.
d. the value of the shirt he purchased start to fall as they wear out over time.
e. the personal value of each additional shirt he purchases starts to fall.