Moe divides his time between studying Physics and studying Economics. His production possibilities curve for his final grade in each class is shown below. If Moe moves from Point A to point C, his grade in Physics will go down by __ his grade in economics

Moe divides his time between studying Physics and studying Economics. His production possibilities curve for his final grade in each class is shown below. If Moe moves from Point A to point C, his grade in Physics will go down by __ his grade in economics.
A.less than the decrease in
B.more than the increase in
C.less than the increase in
D.more than the decrease in
正确答案：less than the increase in