Which of the following statements best explains
why the lower mantle of Earth is much more
rigid and dense than the upper mantle?
A. The lower mantle is older than the upper
mantle.
B.
The lower mantle is cooler than the upper
mantle.
C.
The lower mantle is under more pressure
than the upper mantle.
D. The lower mantle is farther from the core
than the upper mantle.