Using the Graph Below,why Is the Outer Core Liquid,but the Inner

Using the graph below,why is the outer core liquid,but the inner core solid?

A) because the inner core is made of different material than the outer core
B) because the temperature in the inner core is above that of the melting curve
C) because the temperature in the inner core is below that of the melting curve
D) because the pressure on the inner core is lower