A College Student Decides to Spend the Afternoon Watching Three

A college student decides to spend the afternoon watching three movies rented from Red Box.The cost of each movie is $1.The student was willing to pay $4 to rent each of the first two movies and $2 to rent the third movie.What was the marginal benefit received by the student when renting the 1st movie?

A) $1
B) $8
C) $4
D) $2