The correct option is A Sarcomere
A sarcomere is the smallest contractile unit of the muscle, which extends from the Z-line to the next, i.e. region between two successive Z-lines. So the Z-lines mark the boundaries of the sarcomeres. The dark staining region in the center of the sarcomere is called the A (anisotropic) band. The lighter staining band, through which the Z-line passes is called the I (isotropic) band.
Sarcosome is the mitochondria of the muscle cell.
A fascia is a band or sheet of connective tissue, primarily collagen, beneath the skin that attaches, stabilizes, encloses, and separates muscles and other internal organs.