Answer:
A) a white main-sequence star.
Step-by-step explanation:
The main-sequence is the region of the Hertzsprung-Russell diagram ( HRD) in which is found the majority of the stars continuously and distinctively. The stars in the main-sequence (the sun included) are the most numerous stars in the universe. As can be seen from the illustration (the HRD), the hottest stars are white ones: