Torque (of a couple) and centre of gravity MCQ

[Originaltitle]

Homework Statement

Homework Equations

I know torque of a couple = One of the forces x the distance between the 2 forces.

The Attempt at a Solution

I don't know how to approach this blasted problem. Any help would be very much appreciated.

 

[Doc Al]

What torque does the weight of the cube exert about that axis?

 

[CWatters]

What do you know about the forces (or torques) acting on an object that isn't moving or which you don't want to move (or rotate)?