I think it may be A) Plant cycle
B. Wind.
A abiotic factor is non-living, making a, c and d wrong.
Answer:
Muscles contract through a chain process of electrochemical signalling between the nervous system and muscles.
Explanation:
The muscle contraction is initiated by the nervous system by sending a signal. This signal also referred to as action potential travel through the motor neuron. This motor neuron releases a chemical signal to muscle when the electrical signal carried by it reaches the neuromuscular junction (a junction where motor neuron meets the muscles).
The chemical message referred to as neurotransmitter binds to the receptors present on the muscle fibers. These receptors causes the influx of sodium ion which in turn trigger the release of calcium ion thereby initiating the contraction of muscles.
The answer is C Nucleus PLZ vote brainliest.
