The Marginal Cost to an Individual of an Activity, Such

The marginal cost to an individual of an activity, such as attending a concert, increases as additional hours are committed because:

A) firms charge proportionately more for longer activities.
B) each additional hour committed to the activity provides the individual with less utility.
C) the first hour committed comes at the expense of the least important alternative activity, and each hour thereafter requires forgoing more important alternative activities.
D) all of the above.