In a closed system that has 85 J of mechanical energy, the gravitational potential energy of a weight being lowered by a pulley decreases from 12 J to
9 J. How does the system's kinetic energy change if there is no friction?
O A. It decreases from 76 J to 73 J.
O B. It increases from 85 J to 94 J.
O c. It decreases from 85 J to 76 J.
O D. It increases from 73 J to 76 J.