To solve this problem, we need to analyze the events that occur during muscular contraction. Let's examine each statement:$\newline \bullet$(a) ‘H’ zone disappears:$\newline$ - During muscle contraction, the actin filaments slide over the myosin filaments, causing the ‘H’ zone, which is the region of the A band where there is no overlap between actin and myosin, to disappear.$\newline$ - This statement is correct.$\newline \bullet$(b) ‘A’ band widens:$\newline$ - The ‘A’ band represents the length of the myosin filaments and does not change in width during contraction.$\newline$