The early paleozoic era was the time of the cambrian explosion. what happened during the cambrian explosion? a. earth was undergoing lots of contractions as it cooled off. b. there were frequent earthquakes and lots of volcanic eruptions. c. earth was bombarded by a great number of asteroids and comets. d. many new life-forms appeared, including most of the known types of invertebrates.

the answer is A hope this helps

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