Question

which statement about the earths mantle is true?
it is twice as dense as the core
convection in this layer causes the plates to move
it is the outermost layer and is over 2000 km thick
it is the innermost layer with the lowest density

Explanation:

1. Analyze "It is twice as dense as the core": The core (especially the inner core) is denser than the mantle, so this is false.
2. Analyze "Convection in this layer causes the plates to move": Convection currents in the mantle's asthenosphere drive tectonic plate movement, this is a correct concept.
3. Analyze "It is the outermost layer and is over 2000 km thick": The outermost layer of Earth is the crust, not the mantle, so this is false.
4. Analyze "It is the innermost layer with the lowest density": The innermost layer is the core, and the mantle is not the innermost, also the core is denser than the mantle, so this is false.

Answer:

B. Convection in this layer causes the plates to move