For the following questions, imagine the book drops in free fall and falls a distance d. For the system of the book and earth, the change in total energy of the system if the book falls a distance d .(A) is positive.(B) is negative.(C) is zero.(D) has a sign which cannot be determined.

C) is zero

Explanation:

According to the law of energy conservation, the total mechanical energy of the object is conserved. A book falling a distance d would have a change in potential energy, resulting in the same change in kinetic energy. But the total mechanical energy must be the same. So there's 0 change in total energy of the system.