To determine the state of the body resting on a rough inclined plane, let's analyze the forces acting on it.

Concept: A body on an inclined plane experiences components of gravitational force: one perpendicular to the plane and one parallel to the plane. Friction opposes the motion along the plane.

Given: The frictional force is equal to the component of weight along the plane.

In this scenario:

1. The gravitational force acting on the body can be divided into two components:
   • W \sin \theta: parallel to the plane
   • W \cos \theta: perpendicular to the plane
   where W is the weight of the body and \theta is the angle of inclination.
2. The frictional force opposes the component of gravity parallel to the plane.
   • If the frictional force is equal to W \sin \theta, it means that there is no net force acting along the plane.
3. Since forces parallel to the plane are balanced (frictional force = gravitational component):
   • The body is neither moving nor accelerating along the plane.

Conclusion: The body is in equilibrium when the forces are balanced, meaning no net force causes motion or acceleration along the plane. Therefore, the correct answer is equilibrium.

Explanation of Options:

1. Free fall: The body would be accelerating downward with no friction; not applicable here.
2. Acceleration: Would require an unbalanced force; not the case here.
3. Uniform motion: Implies constant speed due to balance of friction and other forces, but not purely balance-related; hence not a perfect fit.
4. Equilibrium: All forces are balanced; the body does not move. This fits the scenario.