Question

1. how are stars classified by their spectral class? a. by their age and size b. by their color and temperature c. by their distance from earth

Explanation:

Stars are classified into spectral classes (O, B, A, F, G, K, M) based on their surface temperature and color. Hotter stars are bluer and belong to earlier spectral - classes, while cooler stars are redder and in later spectral - classes. Age, size, and distance from Earth are not the primary factors for spectral - class classification.

Answer:

B. By their color and temperature