Two steel balls that are the same mass and size are rolled with the same force across different level surfaces.
The ball rolling across carpet will come to a stop faster than the one rolling across concrete because of
A) air resistance.
B) friction.
C) gravity.
D) speed.

The ball rolling across the carpet will come to a stop faster than the one rolling across the concrete because of friction.

Two steel balls rolling on two different surfaces would experience similar forces. However, a carpeted surface is more coarse and irregular than a concreted surface.

Thus, the frictional force on the carpeted surface would be more and the ball would stop faster as opposed to the concrete surface.

More on frictional forces can be found here: link

The reason why the ball rolling across carpet will come to a stop faster than the one rolling across concrete is the friction (option B).

Explanation:

The contact surface on which the balls move is different. Irregularities in the carpet cause the ball in it to stop faster. The concrete surface is less irregular, and allows the ball to move a little more and then stop. This is due to friction.

In physics, friction is a force that is capable of opposing movement, since the contact of two surfaces limits its movement. A smooth surface produces less friction than a rough or irregular surface.

Since the friction that stops both balls occurs when they are in motion, it is called dynamic friction, that is, the force that causes a moving body to stop.

Learn more:

Friction link