Science and there is a picture

c solid metal

Explanation:

it's made of iron and nickel

D) solid metal

Explanation:

Unlike the mineral-rich crust and mantle, the core is made almost entirely of metal—specifically, iron and nickel. The shorthand used for the core's iron-nickel alloys is simply the elements' chemical symbols—NiFe. Elements that dissolve in iron, called siderophiles, are also found in the core.

The inner core is solid because it is made of very dense, or heavy, materials - like iron and nickel. Even though it is very hot, these materials don't "melt" very easily, so they stay solid.

they both have a y in them

answer: the rate of diffusion increases with increase in temperature.

increase in temperature, increases the molecular/particles speed (kinetic energy. diffusion means movement of particles through the material.

generally, the heavier the particle the more it interacts with the environment and more the temperature matters. so higher temperature results in higher diffusion.