The role of calcium in excitation/contraction couple in skeletal muscle is:

• A. by binding troponin C it uncovers the binding site of actin to interact with the myosin head
• B. by binding troponin I, it uncovers the binding site of actin to interact with the myosin head
• C. by binding to tropomyosin, it allows troponic to bind to myosin
• D. by binding to troponin C, it allows the myosin head to disengage resulting in relaxation
• E. it causes depolarisation to spread along the tubules