Question

What causes the Inner Core to be a solid?

Very cold temperatures

Pressure and weight from the outer layers

Continental Drift

Answer 1

Neither continental drift nor very cold temperatures cause the inner core to be a solid. The main factor that causes the inner core to be a solid is the pressure exerted by the outer layers of the Earth. The inner core is under immense pressure from the weight of the surrounding layers, which causes the iron and nickel in the inner core to remain in a solid state despite the high temperatures.