Answer:
Option D, a small main sequence star
Step-by-step explanation:
A red dwarf is just like a small main sequence star as it is formed in the same way as a main sequence star. They are of very small size equivalent to 8 to 50 % of the mass of the sun. They get reduced in size due to their lower burning temperature as they burn using their hydrogen supply less rapidly unlike other main sequence stars which burns their hydrogen supply rapidly