Harlow Shapley First Located the Center of the Milky Way

Multiple Choice

Harlow Shapley first located the center of the Milky Way Galaxy in 1917 by

A) measuring the positions of supernova explosions throughout the Galaxy.
B) observing the distribution of globular clusters in the galactic halo.
C) measuring redshifts of stars in the galactic plane and disk.
D) observing the distribution of hydrogen gas, measured by 21-cm radio emission.