I. All the three forces must be concurrent. II. The upward force is equal to the downward force. III. The algebraic sum of the moment about any point must b...

I. All the three forces must be concurrent.

II. The upward force is equal to the downward force.

III. The algebraic sum of the moment about any point must be zero.which of the above conditions must hold for a body acted upon by a system of three coplanar forces equilibrium?