Answer:
In chemistry, reactivity is a measure of how readily a substance undergoes a chemical reaction. The reaction can involve the substance on its own or with other atoms or compounds, generally accompanied by a release of energy. The most reactive elements and compounds may ignite spontaneously or explosively.
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Pre-Cambrian Era. Earth formed and became a planet 600-3,300 million years ago.
Paleozoic Era. Ancient life. Volcanoes and mount formed.
Mesozoic Era. Middle life (Industrial Ages, Evolution of human technology)
Cenozoic Era. Present life
Answer:
C) Autonomic Nervous System .
Explanation:
