Five ramps lead from the ground to the second floor of a workshop, as sketched below. All five ramps have the same height; ramps B, C, D and E have the same length; ramp A is longer than the other four. You need to push a heavy cart up to the second floor and you may choose any one of the five ramps. Assuming no frictional forces on the cart, which ramp would require you to do the least work?

1. Same work for ramps B, C, D or E; more work for ramp A.

2. Same work for the straight ramps A and B; less work for ramps C, D, and E.

3. Ramp D.

4. Ramp E.

5. Ramp B.

6. Ramp A.

7. Ramp C.

8. Same work for all five ramps.

9. Unable to determine without knowing the exact profiles of ramps C, D or E.