Final answer:
A main sequence star becomes a red giant after using up its core hydrogen and eventually evolves into a white dwarf.
Step-by-step explanation:
A main sequence star, like the Sun, evolves through several stages until it becomes a white dwarf. The first stage after using up its core hydrogen is the red giant stage. As the star runs out of hydrogen fuel in its core, it begins to burn helium, causing its outer layers to expand and the star to become larger and cooler. Eventually, the outer layers are expelled, forming a planetary nebula, and the remaining core collapses and becomes a white dwarf.