A skydiver jumps out of a plane and begins to accelerate. His speed increases to 20 m/s, then 30 m/s. Which correctly describes his kinetic energy during this time
A. His kinetic energy increased while his speed increases, then it became constant
B. His kinetic energy would remain the same for the whole fall as long as he lost no mass
C. His kinetic energy increased quickly at first, then it increased at a constant rate
D. His kinetic energy was positive at first, but it decreased to zero when he stopped accelerating