29. What is the function of Ca2+ in muscle contraction? (A) It binds to myosin to promote its dissociation from actin. (B) It binds to troponin to trigger a conformational change in a troponin-tropomyosin complex. (C) It binds to actin to promote its dissociation from myosin. (D) It binds to myoglobin to promote oxygen binding.