Answer:
Tropomyosin
Step-by-step explanation:
The calcium binding to troponin and induces the muscle contraction. The active binding site gets exposed due to the calcium binding.
The calcium ions then attaches with troponin molecule. This changes the shape of troponin and removes the tropomyosin protein from the binding site. No ATP is available during this process.
Thus, the correct answer is option (d).