An object slides down a rough inclined plane with some non-zero acceleration a1. (There is friction).The same mass is shoved up the same incline with a large, brief initial push. As the mass moves up the incline, its acceleration is a2. Which of the following statements about the magnitudes of these accelerations is true?

a. a1=a2
b. Not enough information
c. a1> a2
d. a2> a1