The answer is letter A. meteorite bombardment.
During the Earth's earliest beginning, it went through a period of catastrophic and intense formation. By 3-8- 4.1 billion years ago, Earth's atmosphere was never the same as today. This is because of its formation during the pre-Cambrian period whereby the Earth formed under so much heat and pressure that it formed as a
molten planet.
Earth was bombarded continuously by the remnants
of the dust and debris — like asteroids, meteors and comets — until it formed
into a solid sphere, pulled into orbit around the sun and began to cool down during the Hellish period (4.5 to 3.8 billion years ago).
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