Question

multiple choice question
kinetic friction is the force exerted on one surface by a second surface when the two surfaces rub against each other because one or both of the surfaces
o have just stopped moving.
o are stationary.
o are about to move.
o are moving.

Explanation:

Kinetic friction occurs when two surfaces are in relative motion (moving) with respect to each other. Static friction acts when surfaces are stationary or about to move. When surfaces have just stopped moving, static friction might come into play depending on the situation, but kinetic friction specifically requires motion.

Answer:

are moving.