Answer:
The correct would be option b.
It can be explained with the help of the H zone.
H zone is the region of the muscle which consists of only the thick filament, that is, myosin.
In a relaxed state, the thickness of the H zone is more as compared to the contracted state.
In the contracted state, the myosin pulled the actin fibers towards the M line due to which thickness of H zone decreases.
