Question

Due to density variation -------is formed between two plates​

Answer 1

collision

I think this is correct

Answer 2

Due to density variation mountain is formed between two plates.

Explanation:

• When two plates of same density or different density collide with each other, it will lead to formation of a mountain.
• This is how all the mountains such as Himalayas and every other greater mountains were formed in ancient times.
• This is what happened even to the smaller mountains.
• This is the science behind plates and mountains.