The core of Earth is made out of iron and nickel. The outer core's temperature is so hot that it melts the metal. The inner core is solid metal. What causes these differences?
A. The outer core is is 2,2,300 300 km thick.
B. The inner core is kept solid by the intense pressure of all of the layers above it.
C. The inner core has a cooler temperature, allowing the metal to remain solid.
D. The inner core is made of a different metal.