Answer
1. c)
2. a)
3. b)
Work Step by Step
1. The kinetic energy (and other energies) are not changing because the ball's speed and height are constant, so no work is done.
2. The ball speeds up and begins to go upward, so positive work is done, for the ball has gained energy.
3. The ball loses speed and thus energy as well to the surroundings. As a result, negative work is done on the ball.
