Which of the following is not an example of work?
a. raising a barbell over your head
b. picking up a box off the floor
c. holding a tray in the cafeteria line
d. pushing a box across the floor

The following which is not an example of work is C. holding a tray in the cafeteria line because if force displaces an object it should work. I think it's clear and I am pretty sure this answer will help you.

Are a.larger