Generally speaking, how does the surface temperature and luminosity of a protostar compare to the surface temperature and luminosity of the main-sequence star it becomes?
A) A main-sequence star is hotter and brighter than it was as a protostar.
B) A main-sequence star is cooler and dimmer than it was as a protostar.
C) A main-sequence star is cooler and brighter than it was as a protostar.
D) A main-sequence star is hotter and dimmer than it was as a protostar.
Answer: D