What Will Happen in the Sun Immediately After It Has

What will happen in the Sun immediately after it has exhausted its supply of hydrogen in its core?

A) The helium core will shrink, heat, and start fusing helium to carbon.
B) The core will collapse and a supernova will result.
C) The Sun will turn into a white dwarf and cool off forever.
D) The helium core will shrink and heat; a shell of hydrogen will start fusing.