A man stands on a spring scale in a moving elevator and notices that the scale reading is 20% larger than when he weighs himself in his bathroom. Which statement can not be true?

a) the elevator could be moving upward at constant speed
b) The tension in the supporting cable must exceed the weight of the elevator and its contents
c) The speed of the elevator changes by equal amounts in equal times.
d) The elevator could be moving upward with increasing speed.