If you received a free month's trial membership in a gym,you would keep going until your marginal utility reached

A) a maximum.
B) zero.
C) a positive number.
D) a negative number.

Marginal utility is the additional satisfaction or benefit derived from each additional unit of a good or service consumed. In the case of a free trial membership at a gym, the marginal utility of going to the gym will decrease over time as the individual becomes used to the experience and gains less satisfaction from it. Eventually, the marginal utility will reach zero or a point where the individual no longer sees any benefit, and they will stop going to the gym. Therefore, the best choice is B, as this represents the point where the individual's marginal utility has reached zero and they will no longer continue going to the gym.