Which stars tend to have the greatest range of temperatures and the highest luminosities?

red giants
white dwarfs
supergiants
main sequence

Option D, Main sequence Stars

Explanation:

The stars which are located between the upper left corner  and the lower right corner of Hertzsprung - Russell Diagram have high temperatures and high  luminosity. For example sun. Sun is a form of main sequence star and thus have have high temperatures and high   luminosity.

While giant and red giant stars have low temperature and high luminosity and a super giant has high luminosity but its temperature may vary from low to high temperature.  

White dwarfs are stars with high temperature and low luminosity

 Thus, among all the given options Option D, is the correct answer.

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