The muscles are made up of fibers. These fibers are called myofibrils. The correct option is A.
What are muscles?
Muscles are soft tissue are made up of fibers. Muscles are of 600 types in the body. They are connected with the bones. Muscles help in running. Walking, sitting, stretching, etc.
Muscle fibers are made up of myofibrils that contain a special type of protein called myoglobin and molecules that provide muscles the oxygen.
Thus, the correct option is A. Fibers, with regard to muscles.
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