Hubble's galaxy classification diagram (the tuning fork) ________.
A) suggests the existence of black holes
B) explains active galactic nuclei
C) shows how galaxies evolve from one form to another
D) relates galaxies according to their shapes, but not according to any evolutionary status
Question 2
White dwarfs like Sirius B are typically the size of ________.
Fill in the blank(s) with correct word