Answer:
Middle layer, density increases with depth as pressure increases
Step-by-step explanation:
The Earth's mantle is the middle layer of the earth. It is the largest layer of the earth consisting of about 83 % of the earth's volume and continues to a depth of 2900 km. Also, the mantle is hot and made of solid rock. It is hot since it is close to the core and its pressure and density increases with depth causing it to be more solid.
So, the Earth's mantle is the middle layer, density increases with depth as pressure increases.