Answer:
D) Coordinated contraction and relaxation of muscle groups
Step-by-step explanation:
In order for muscles to properly work, the muscle groups have to contract and then relax in coordination.
If muscles were to constantly contract, then the muscles would get overworked and fail to function correctly.
If muscles were to constantly relax, then the muscles wouldn't be able to work at all.
If the contraction and relaxation of muscle groups were uncoordinated, then the organism wouldn't be able to have muscle control, which is needed.