The muscle that alds in producing a movement but that is not primarily responsible for the movement is considered the A. Synergist
B. Antagonist
C. Agonist
D. Prime mover

A. Synergist

Explanation:

The muscle that is primarily responsible for a movement is called the

prime mover, also known as the agonist. The muscle that produces a contraction to help in creating the movement but doesn't have the primary responsibility for it is considered the synergist muscle.  

The antagonist muscles are those that resist the change in the prime mover and cause movement in the opposing direction.

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