Select the incorrect statement:
(a) A machine always has efficiency less than 100%.
(b) The mechanical advantage of a machine can be less than 1.
(c) A machine can have mechanical advantage greater than the velocity ratio.
(d) A machine can be used as a speed multiplier.

(c) A machine can have a mechanical advantage greater than the velocity ratio.

Reason — In actual practice, mechanical advantage for all practical machines is always less than its velocity ratio (i.e., MA < VR) or the output work is always less than the input work, so the efficiency is less than 1 (i.e., η < 1 ) due to some loss of input energy against the force of friction etc.