One sarcomere a. extends from Z line to Z line. b. is composed of many myofibrils. c. contains only actin fibers. d. is composed of many muscle fibers. e. surrounds each muscle in the body.

a. extends from Z line to Z line.

Explanation:

A sarcomere refers to the region between two consecutive Z lines. Sarcomere serves as functional units in skeletal muscles as the shortening of individual sarcomeres results in shortening of myofibrils and muscle cells.

Each sarcomere extends from one Z line to the next one and consists of one complete A band and two half parts of an I band. The two halves of the I band are present one either side of A band in a sarcomere.