Sirius is a star with spectral type A star and Rigel is a star with spectral type B star. What can we conclude?
A) Rigel has a higher core temperature than Sirius.
B) Sirius has a higher core temperature than Rigel.
C) Rigel has a higher surface temperature than Sirius.
D) Sirius has a higher surface temperature than Rigel.
Answer: C