Which of the following is a direct source of energy for muscle contraction?

Adenosine Triphosphate (ATP) is the only direct and immediate chemical energy source utilized by the heavy chains of myosin to drive cross-bridge cycles during active muscle contraction. Creatine phosphate works effectively as a high-energy reservoir to rapidly re-phosphorylate ADP into ATP via the creatine kinase reaction, but it cannot be directly broken down by the contractile filaments.