The gravitational acceleration on Earth is 9.8 m/s2. A small marble is dropped to the floor, assume that as the marble falls, the only force exerted on the marble is the force of gravity (there is no air resistance). How do the speed and acceleration of the marble change with time?
A) Speed increases, acceleration increases.
B) Speed remains constant, acceleration increases.
C) Speed increases, acceleration remains constant.
D) Speed and acceleration remain constant.