To solve this problem, we need to understand the role of calcium in skeletal muscle contraction. Let's analyze each option:$\newline \bullet$Option 1: Detaches the myosin head from the actin filament.$\newline$ - This is incorrect. The detachment of the myosin head from actin is primarily due to the binding of ATP to the myosin head, not calcium.$\newline \bullet$Option 2: Activates the myosin ATPase by binding to it.$\newline$ - This is incorrect. Calcium does not directly activate myosin ATPase. Myosin ATPase activity is primarily regulated by the interaction of myosin with actin.$\newline \bullet$Option 3: Binds to troponin to remove the masking of active sites on actin for myosin.$\newline$ - This is correct. Calcium binds to the troponin complex, causing a conformational change that moves tropomyosin away from the active sites on actin, allowing myosin to bind to actin and initiate contraction.$\newline \bullet$Option 4: Prevents the formation of bonds between the myosin cross bridges and the actin filament.$\newline$ - This is incorrect. Calcium facilitates the formation of bonds between myosin and actin by exposing the active sites on actin.$\newline$Therefore, the correct answer is Option 3: Calcium binds to troponin to remove the masking of active sites on actin for myosin.