Consider a vehicle going on a horizontal road towards east. Neglect any force by the air. The frictional forces on the vehicle by the road
Is zero if the vehicle is moving with a uniform velocity
Option (a) says friction force will be in east if car is accelerating.
Well car is going in east direction and if it is accelerating then the net force has to be in east direction. Well there can be no other force than frictional force in horizontal direction. so option (a) is correct.
Option (b) says force is 0 if constant velocity which means 0 acceleration
⇒ 0 net external force so no friction possible as again friction can be the only external force on the body along horizontal line.
Option (c) Must be towards east
Must
Pretty strong word
Well if the acceleration was in east direction then the option would have been correct but since nothing mentioned about it so we can't talk about Net force or its direction
Option (d) same as above both C & D are wrong