Which of the following is the functional unit of a myofibril?

a. sarcomere

b. myofilament

c. sarcolemma

d. endomysium

Sarcomere

Explanation:

Myofibril is the unit of the muscle cell. The myofibril is rod like in structure and developed by the process of myogenesis in embryo.

Sarcomere is the basic structural unit of the skeletal muscles and shows striations under the microscope. Sarcomere consists of thick and thin filaments of actin and myosin. Different bands like A - band, H-Band, I-Band and Z - line is visible in the sarcomere.

Thus, the correct answer is option (A).