What is parasympathetic nervous system

It regulates the body’s rest and digest mechanism. Once stress is reduced the system helps the body return to its normal state and conserve energy by slowing the heart rate, and reducing blood flow to the muscles.

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i think its b

explanation:

humans, along with other animals and plants, have linear chromosomes that are arranged in pairs within the nucleus of the cell. the only human cells that do not contain pairs of chromosomes are reproductive cells, or gametes, which carry just one copy of each chromosome.