What are two processes do scientists think move the earths lithosphere plates?

The CORRECT answer is:

gravity acting on the edges of plates and convection in the mantle

I know this because I am an online student, I got the question wrong on my quiz after I submitted it, and the quiz showed me the correct answer.

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when atoms of different types of elements join together, they make molecules called compounds. water consists of compound molecules made up of 2 hydrogen atoms and 1 oxygen atom. this is why it's called h2o. water will always have 2 times the number of hydrogen atoms as oxygen atoms.