$A$ mass on a spring oscillates up and down. As the mass moves downward from its highest point to its equilibrium point:

• A
  The net force is downward,the net work done on the mass is positive and the mass speeds up.
• B
  The net force is upward,the net work done on the mass is negative and the mass slows down.
• C
  The net force is downward,the net work done on the mass is positive and the mass speeds up.
• D
  The net force is upward,the net work done on the mass is negative and the mass speeds up.