What Provides Us the Best Clues as to the Age

Multiple Choice

What provides us the best clues as to the age of a galaxy like ours?

A) the periods of the fastest-spinning pulsars and Cepheid variables
B) the number of planetary nebulae
C) the observed frequency of high-mass-star supernovae
D) the H-R diagrams of globular clusters of stars
E) the luminosity of the most massive stars