In the diagram of the earths interior, where does the material that forms volcanos come from?
using the same diagram, which part is the densest?

In general the earth's interior has been sorted by Gravity. Heavier elements like iron tend to sink toward the center or core of the earth. Lighter materials, the silicates, oxygen compounds and water have risen to become part of the crust. This action has created distinct layers within the earth and is still in process today.

Bruh i don’t know the answer tbh but you can google it