What are the two variables that are incorporated in the hertzsprung-russell diagram?

a. a star's luminosity (brightness) and its surface temperature
b. a star's age and its surface temperature
c. a star's age and its distance from earth
d. a star's luminosity (brightness) and its distance from earth

the most common type of reef is the fringing reef. this type of reef grows seaward directly from the shore. they form borders along the shoreline and surrounding islands.

the sun's light combined with the visible wavelenghts form what is called ultraviolet radiation, which are the long waves at the end of a visible light sprectrum.

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bioteacher101