Muscles have different roles when an exercise is carried out, in fact there are multiple muscles working in different ways whenever we move.
The name given to the muscle that relaxes when the prime mover contracts.
The name given to the muscle that is the prime mover for a given joint action.
The name given to the muscle that assists the main muscle (prime mover)in bringing about the action.
The muscle that contracts to stabilise the part of the body that remains fixed, e.g the trapezius stabilising the shoulder girdle or the transverses abdominus stabilising the vertebrae.
Now see if you can match those up correctly!