The four claims I to IV below concern conservative forces, potential energy and mechanical energy. Pick the option listing exactly the true claims.

• I. The work done by a conservative force on a body moving around any closed path is zero.
• II. A potential energy function can be defined only for a conservative force.
• III. The total mechanical energy of a body remains constant even while kinetic friction acts on it.
• IV. The work done by a conservative force depends only on the initial and final positions of the body.