You are answering a USMLE-style medical question. Question: A scientist is studying the properties of myosin-actin interactions in a sample of human muscle tissue. She has identified a drug that selectively inhibits phosphate release by the myosin head. If she gives this drug to a sample of human muscle tissue under physiologic conditions, which of the following steps in cross-bridge cycling will most likely be blocked? Options: A) Myosin head cocking B) Exposure of myosin-binding sites on actin C) Myosin head binding to actin D) Power stroke Reply with ONLY the letter of the correct answer (A, B, C, or D). No explanation.