Question

which property of a star is closely related to its temperature?
brightness
color
composition
size

Explanation:

Stars emit light across a range of wavelengths. The dominant wavelength of light (which relates to color) is determined by the star's temperature. According to Wien's displacement law, hotter stars emit more energy at shorter wavelengths (bluer colors), and cooler stars emit more at longer wavelengths (redder colors). Brightness is related to luminosity (which depends on size and temperature), composition is about the elements in the star, and size is a separate property not as directly tied to color - temperature relationship as color is.

Answer:

B. color