Choice-a is a very rubbery, imprecise, ambiguous, slippery statement. But it's probably less wrong than any of the other choices on the list.
Friction as it will move charge (electrons) from one object to another
The bigger the object the greater the gravitational pull, so the farther away the big object is its gravitational force begins to decrease. Refer to the picture for more explanation.
Answer: Subtract the kinetic energy of the block at x=0.02mx=0.02m from the kinetic energy of the block at x=0.00mx=0.00m.
Explanation: