The Two Most Important Processes in Heating the Interiors of the Terrestrial

The two most important processes in heating the interiors of the terrestrial worlds are:

A) (1) heat deposited by the process of formation; (2) heat released by radioactive decay.
B) (1) heat deposited by the process of formation; (2) heat that came from the gravitational potential energy of incoming planetesimals.
C) (1) heat from convection; (2) heat from thermal radiation.
D) (1) volcanism; (2) tectonics.