To order the stars from smallest to largest, we consider their types and sizes.
- A white dwarf is a small, dense remnant of a star that has exhausted the nuclear fuel for fusion and has collapsed to a very small size.
- The Sun is a medium-sized star, classified as a G-type main-sequence star (G dwarf).
- A red supergiant is much larger than the Sun, representing an advanced stage in the life cycle of massive stars.
Therefore, the correct order from smallest to largest is:
white dwarf, Sun, red supergiant
So, the response is:
white dwarf, Sun, red supergiant.