Question

match the letters with the groups of stars found on the h - r diagram below:
effective temperature (k)
25,000 10,000 6,000 3,000
-10
10^4
luminosity (l*/l_sun)
10^2
0
+5
10^-2
+10
d
10^-4
+15
o b a f g k m
spectral class
hertzsprung - russell diagram
a
b
c
d
supergiants
red giants
white dwarfs
main sequence

Explanation:

On the Hertzsprung - Russell (H - R) diagram, the main sequence is a band of stars that runs from the upper left (hot, luminous stars) to the lower right (cool, less - luminous stars). Red giants are large, cool, and luminous stars located above the main sequence. Supergiants are even more luminous and larger than red giants, at the top of the diagram. White dwarfs are small, hot, and low - luminosity stars located at the bottom left of the diagram.
A is on the main sequence. B is a red giant. C is a supergiant. D is a white dwarf.

Answer:

A. Main Sequence
B. Red Giants
C. Supergiants
D. White Dwarfs