During skeletal muscle contraction:: (A) A band shorten, (B) Both H and I band shorten, (C) Both A and I band shorten, (D) Both A and H band shorten
Answer is B. During  muscle contraction,  two Z lines come  closer;  the  length  of  the  ‘A  band’ remains constant whereas the length of H and I band decreases. The M line becomes more prominent.