The person using the track with the rollers uses less energy to load the box because the rollers reduce the
1) mass of the box
2) distance traveled by the box
3) force of gravity
4) force of friction

Option 4

Explanation: Suppose that you initially have a plane ground, and you want to move a box in it, all the surface of the box is touching the ground, so the force of friction affects the box motion.

Now, if you have rollers, the surface of the box is touching rollers, now, when you push the box the rollers will start a "rotational" movement, this is because the force of static friction on the external side of the rollers (force that appears when the person wants to move the box) creates an opposite force in the roller itself that makes it rotate, and this rotation "pushes" the box forward.

Now, this is an ideal case, of course, there will be some sliding of the box, that causes a little of the force of friction (dinamic) against the motion, but in this case, the rollers are helping in the motion and "absorbing" some of that force, so the force of friction on the box will be smaller.

b.

explanation:

10.0

it would be kevlar ^^