In thinking back to the 6th Mass Extinction documentary, how many mass extinction events have already happened on Earth?

it is a

explanation:

here is the answer

water, ice, acids, salts, plants, animals, and changes in temperature are all agents of weathering. weathering is the breaking down or dissolving of rocks and minerals on earths surface. once a rock has been broken down, a process called erosion transports the bits of rock and minerals away.