Question

the area between z lines is the
○ sarcolemma.
○ myofilament.
○ sarcoplasmic reticulum.
○ sarcomere.
○ myofibril.

Explanation:

The sarcolemma is the muscle cell membrane, myofilaments are the contractile protein strands, sarcoplasmic reticulum is the calcium-storing organelle in muscle cells, myofibrils are the thread-like structures made of sarcomeres, while the sarcomere is defined as the functional unit of muscle, spanning between two adjacent Z lines.

Answer:

sarcomere.