Explanation:

For equilibrium, the net moment acting on the body by various conservative forces must be zero. This means that the sum of the moments produced by all the conservative forces acting on the body should be equal to zero.

Moments:
- A moment is the turning effect of a force about a point or axis. It is a measure of the tendency of a force to rotate an object around an axis.
- Moments are calculated by multiplying the force by the perpendicular distance from the point or axis of rotation.
- Moments can be either clockwise or counterclockwise, depending on the direction of the force and the direction of rotation.

Conservative Forces:
- Conservative forces are those forces that conserve mechanical energy.
- Examples of conservative forces include gravity, elastic forces, electric forces, and magnetic forces.
- Conservative forces have the property that the work done by the force depends only on the initial and final positions, and not on the path taken between the positions.
- This means that the work done by conservative forces is path-independent.

Equilibrium:
- Equilibrium occurs when an object is at rest or moving with a constant velocity.
- In equilibrium, the sum of the forces acting on the body is zero (ΣF = 0) and the sum of the moments acting on the body is zero (ΣM = 0).

Net Moment and Equilibrium:
- The net moment is the sum of all the moments produced by the individual forces acting on the body.
- If the net moment is zero, it means that the clockwise moments and counterclockwise moments balance each other out, resulting in no overall tendency for the body to rotate.
- When the net moment is zero, the body is in rotational equilibrium.

Conclusion:
- In conclusion, for equilibrium, the net moment acting on the body by various conservative forces must be zero.
- This is because equilibrium requires both the sum of the forces and the sum of the moments to be zero.
- Therefore, option 'A' is the correct answer.