Which of these binaries would appear most similar in color ...

[dejastew]

Which of these binaries would appear most similar in color telescopically?
 
  A) O2V and M4Ia
  B) M1V and K9V
  C) A2Ia and F7Ia
  D) F3IV and G8III
  E) F0V and G9III

Question 2

While we know of thousands of quasars, it is likely none of them still exist today. Explain.
 
  What will be an ideal response?

[Brummell1998]

Answer to Question 1

B

Answer to Question 2

Quasars are associated with the gravitational collapse that gives birth to galaxies, and as they sweep up the accreting matter around them, soon their supply of fuel must become depleted, and they evolve into normal galactic nuclei; Seyfert galaxies are probably good examples of this change. No quasar has been observed closer than a billion light-years distant, so the last ones probably died out a billion years ago.

[dejastew]

Thank you!

[Brummell1998]

Always glad to help...