Work done by a body against friction always results in . . .

Question : Work done by a body against friction always results in 
(a) loss of potential energy 
(b) gain in potential energy 
(c) loss in kinetic energy 
(d) gain in kinetic energy 

Doubt by Jaskirat

Solution : 

As we know that friction is a force that acts between two surfaces in contact, and it always opposes the relative motion between them. This means that when a body is moving against friction then its velocity will decreases and as a result its kinetic energy will also decreases so there must be some loss in kinetic energy. 

Hence, (c) loss in kinetic energy, would be the correct option.