When a sarcomere contracts and thin filaments move over thick filaments you would expect to see
a. the i bands to appear wider
b. the i bands to appear smaller
c. the h zone to appear wider
d. the a band to appear darker

the I bands to appear smaller

Explanation:

I band is the lighter and a less dense area of the sarcomere. It contains no thick filaments. A Z disc passes through the center of each I band.  During muscle contraction myosin heads become attach to and slide along the thin filaments at both ends of a sarcomere. It pulls the thin filaments toward the M line and makes the thin filaments slide inward and meet at the center of a sarcomere. This inward movement of thin filament allows their ends to overlap.

As the thin filaments slide inward, I band and H zone narrower. I band and H zone become disappear altogether when the muscle is maximally contracted. The width of the A band and the lengths of the thick and thin filaments remain unchanged.

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