Plays a critical role as a neurotransmitter that stimulates skeletal muscles to contract.

Acetylcholine plays a critical role as a neurotransmitter that stimulates the contraction of skeletal muscles.

Explanation:

Acetylcholine is a neurotransmitter, a chemical released by nerve cells to send signals to other cells. It was the first neurotransmitter to be discovered. It is also the most abundant neurotransmitter and is present in both the central nervous system and the peripheral nervous system.

Acetylcholine is the main neurotransmitter of the autonomic nervous system, which has such important functions as contracting smooth muscles, dilating blood vessels, increasing body secretions and decreasing heart rate. Another of its main functions is to fulfill the role such as waking up, maintaining vigil and attention, as well as in processes related to the ability to perceive different sensations and make decisions based on them.

Another important role of acetylcholine in the central nervous system is that it is involved in achieving REM type sleep, learning and the plasticity of the nervous system.

it's c. (to reduce the greenhouse effect/carbon gasses)

desert perennials often survive by remaining dormant during dry periods of the year, then springing to life when water becomes available. most annual desert plants germinate only after heavy seasonal rain, then complete their reproductive cycle very quickly.