题目内容：

marginal
marginal cost of an activity is a measure of__the activity.
A.what is forgone with every one unit increase in
B.the total cost of
C.the benefit derived from every one unit decrease in the benefit derived from every one unit decrease in
D.the benefit derived from e
E.sun cost ofvery one unit decrease in the benefit derived from every one unit increase in
C.the benefit derived from every one unit decrease in
D.C.the benefit derived from every one unit increase in
E.sunk cost of