A- Temperature.
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The brain's suprachiasmatic nucleus regulates the body's circadian rhythms. The suprachiasmatic nucleus is a minute region of the brain located in the hypothalamus above the optic chiasm, the circadian rhythm is the 24-hour cycle of organisms, related to sunlight and temperature.
Evolution occurs when<span>these heritable differences become more common or rare in a population, either non-randomly through natural selection or randomly through genetic drift
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