Answer:
The sum of all forces on the object are zero
Step-by-step explanation:
An object in equilibrium means it is balanced. In an equilibrium state, the total forces acting on it are balanced so net force is zero and then the system is said to be in equilibrium state.
For example : In attached figure, the forces acting in horizontal as well as vertical direction are equal and opposite. This gives the sum of forces acting on the object is zero. So, the system is in balanced state or in equilibrium state.
Hence, the correct option is (c).