Balancing of Multiple Mass in Multiple Plane

What are the necessary conditions in order to have a complete balance of the several revolving masses in different planes? Which of the following statements are correct?
A. The couples about the reference plane must balance
B. The forces in the reference plane must balance
Rotation in different planes require the balancing of-
Cause of unbalance-
Which of the following statements is correct about the balancing of a mechanical system?