Answer:
Your answer is B
The reason why B is right is that even though gravity is pushing down on the marble it is also causing it to go down the ramp. As the marble rolls down the ramp, it gathers speed because it starts out slow and as it gets closer to the ground/table it gets faster because of the revolutions per second that the marble takes while going down.
I'm not sure if this makes sense to you or not. I'm sorry if it doesn't.
Hope This Helps!