Answer:
Option B, electrochemical signals
Explanation:
The first process that initiates the muscle contraction is the binding of calcium ion with troponin protein. After this chemical interaction, the active binding sites of actin gets exposed. After this myosin binds to the actin sites thereby forming a high-energy head bridge and releasing the pi. Mysosin now goes to a lower energy state by undergoing conformational change. This causes power stroke and actin filament is pulled towards the M-line. Later on the muscle contracts by shortening sarcomere.
This entire process is an electrochemical process. hence option B is correct.
