Tara Notices That Studying for 1 Hour After Class Increases

Multiple Choice

Tara notices that studying for 1 hour after class increases her economics grade by 11 points.The second hour yields a 7-point gain,the third hour yields a 4-point gain,and the fourth hour yields only a 1-point gain.This means that the marginal _____ of studying decreases with study hours.

A) cost
B) benefit
C) opportunity cost
D) time