A) When a body slides on rough surface, its momentum is not conserved.
B) When a ball falls from a height, momentum of earth ball system is conserved.
C) In case of explosion of flying bomb, momentum is conserved.

detailed solution

Correct option is B

When a flying bomb explodes, external force acting on the the system is the gravity force. But force of gravity is not an impulsive force and also this gravity force is much smaller than the force of explosion, so option (C) is true. Earth is pulling the falling ball, also the ball is pulling the earth by same force. so net external force on the earth-ball system is zero. Therefore statement -B is true. When a body slides on a rough surface, external force acting on the body is force of friction, so momentum is not conserved.