The sun makes its own energy through a process called

a. radiation
b. combustion
c. nuclear fusion
d. nuclear fission

nuclear fusion, because it combines the atoms to create massive amounts of heat, and energy, if it were radiation, it'd just be a giant ball of stale power that wouldn't do anything, and you should already know that the sun doesn't explode to create energy. As applies for fission, it doesn't deconstruct it's self to create energy

hope this helps!