A box is pulled a distance d across the floor by a force F which makes an angle 6 with the horizontal (see figure below). If the magnitude of the force were kept constant but the angle 6 were increased, the work done by the force would

a. increase.
b. remain the same.
c. either increase or decrease, depending on the magnitude of the force F.
d. decrease.
e. either increase or decrease, depending on what the initial angle theta was.