The structural and functional unit of skeletal muscle is known as:

Correct option is A

The sarcomere is the structural and functional unit of skeletal muscle, responsible for contraction. It lies between two Z-lines and is composed of actin and myosin filaments whose interaction leads to muscle contraction, giving skeletal muscles a striated appearance. Explanation for each option: (a) Sarcomere: Correct. Sarcomere is the smallest contractile unit in skeletal muscles and is crucial for muscle contraction and movement. (b) Micromere: Incorrect. Micromeres are small blastomeres formed during embryonic development and are unrelated to muscle structure. (c) Macromere: Incorrect. Macromeres are large cells in early embryonic stages, not connected to skeletal muscles. (d) Nephron: Incorrect. Nephron is the structural and functional unit of the kidney involved in urine formation, not muscle contraction.