Answer:
An asteroid impact.
Explanation:
An asteroid impact is considered to have tossed rubble across the earth, killing off many species of plants and animals, 65 million years ago. Volcanic activity is involved in at least four mass extinctions, whereas an asteroid in just one.
Answer:
I think B because white blood cells fight off bacteria and stuff. I hope this is right for you! if not I am sorry! Have a great holiday.
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