Adam lifts a book from the floor, carries it across the room, and places it on a high shelf. When is Adam doing work on the book?
Work = Force × Distance
A. He does work on the book at no time during this process.
B. He does work as he picks up the book and as he lifts it to the shelf.
C. He does work from the moment he touches the book until he lets it go.
D. He does work only while he carries the book across the room.