A stone of mass m is tied to an inelastic string of length L and whirled in a circle, then

The correct option is B The motion will be a non uniform circular motion, if the motion was a vertical circle
Unlike horizontal circular motion, in vertical circular motion the speed, as well as the direction of the object, is constantly changing. Gravity is constantly either speeding up the object as it falls, or slowing the object down as it rises.
The correct option is (b)