Question

during muscle contraction the _________ move closer together.
a z lines
b i bands
c h bands
d m lines
e a bands

Explanation:

During muscle contraction, the sliding filament theory states that the thin filaments (actin) slide over the thick filaments (myosin). The Z - lines demarcate the boundaries of a sarcomere. As the thin filaments slide towards the center of the sarcomere (M - line), the Z - lines move closer together. The I - band (contains only thin filaments) and H - band (contains only thick filaments) shorten during contraction. The A - band (contains both thick and thin filaments) remains the same length. The M - line is the mid - line of the sarcomere and does not move closer to other structures in the way described in the question.

Answer:

A. Z lines