Aidan lifts a box from the floor, carries it across the room, and places it on a high shelf. When is Aidan doing work on the box?
a
He does work only while he carries the box across the room.
b
He does work as he picks up the box and as he lifts it to the shelf.
c
He does work from the moment he touches the box until he lets it go.
d
He does work on the box at no time during this process.