Which of earth's layers is about the same temperature as the surface of the sun?

a. lower mantle
b. upper mantle
c. outer core
d. inner core

The correct answer is inner core.

The highest temperature of the Earth lies in the inner core which resembles the temperature of the sun.

The temperature in the solid inner core can reach upto 9,000 degrees Fahrenheit.  

The inner core is made of iron and nickel.

The movement of inner core and outer core creates magnetic field.  

not too sure maybe olecranon process