Answer: b. The temperature at the Earth's center may almost equal the temperature of the Sun's surface.
Step-by-step explanation:
The Earth's core is very very hot due to various factors such as heat from radioactive materials decaying and the heat the earth had when it was formed. It is estimated that the temperature here is around 5,200° C which means that it can melt even Tungsten.
This is almost equal to the surface temperature of the sun which is around 5,500° C.