A 50 gram cart is connected to a spring whose unstretched length is 10 cm and whose spring constant is 2.5 N/cm. The motion of the mass is initiated by a person pulling the mass 5 cm to the right of its equilibrium position and releasing it. Ignore friction and air resistance in this problem. At the time the situation occurs, indicate whether the force vector requested points left (L), right (R), or has magnitude zero (0).

a. The force on the mass exerted by the spring when the mass is at its equilibrium position and is at rest. b. The force on the mass exerted by the spring when the mass is at its equilibrium position and is moving downward. c. The net force on the mass when the mass is at its equilibrium position and moving downward. d. The force on the mass exerted by the spring when it is at the top of its oscillation. e. The net force on the mass when it is at the top of its oscillation.