They provided silk
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I think this is the answer...
Warm air is increasing to create low pressure zone; cool air is falling, creating a high pressure region. Air pressure and climate are rising warm air. Winds cause weather that moves across high-and low-pressure areas horizontally. The faster the wind moves, the higher the pressure difference between the pressure zones.
Answer:
Genetic variation.
Explanation:
It is caused by genes inherited from parents to offspring. It is a result of genetic information from parents.
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