A body can be put into equilibrium by applying a force equal in magnitude but opposite in direction to the:

The correct answer is the equilibriant. In physics, when we talk about equilibrium, we refer to a state where all the net forces acting on a body are balanced. This means that if we were to apply a force that is equal in magnitude but opposite in direction to the resultant of all the other forces acting on the body, it would bring the body into a state of equilibrium.

The resultant force is the vector sum of all the forces acting on an object. It determines the overall effect of those forces. To achieve equilibrium, a force must be applied that directly counteracts this resultant force. This opposing force is known as the equilibriant.

In contrast, scalar quantities do not have a direction associated with them, and therefore cannot help in determining equilibrium. While vectors represent quantities that have both magnitude and direction, in the context of this question, the term specifically needed is the equilibriant, which directly relates to forces and their effect on achieving a balanced state.