What is the class of luminosity that indicates the size of a star compared to stars of the same spectral type?

The class of luminosity is designated by Roman numerals.
The lower the Roman numeral, the larger the star.
Supergiants are designated by classes I and II.
Dwarfs of the main sequence are designated by class V.
a) I, II, and III are correct.
b) II, III, and IV are correct.
c) I, III, and IV are correct.
d) II and IV are correct.