The correct answer is "velocity, height". Kinetic energy is affected by: mass and velocity, while potential energy by: mass, gravity and height (or "position"). Considering these combinations, only the third choice is the correct one: a) position, gravity describe only potential energy, B) gravity, position describe only potential energy, C) velocity, height describe respectively kinetic and potential energy, D) height, velocity would respectively describe potential energy first and then kinetic energy, it is in the wrong order, thus the correct answer is C.
