Imagine you are digging a hole to the center of the earth. In which order would dig through them?
A. inner core, outer core, upper mantle, lower mantle, crust
B. crust, upper mantle, lower mantle, outer core, inner core
C. crust, outer core, inner core, upper mantle, lower mantle
D. inner core, outer core, lower mantle, upper mantle, crust