What Does the Equivalent of an H-R Diagram for Galaxies,plotting

Multiple Choice

What does the equivalent of an H-R diagram for galaxies,plotting luminosity versus color,show?

A) galaxies fill the diagram showing that there is no correlation between luminosity and color
B) two clumps,one blue with relatively low luminosity,one red with relatively high luminosity,and a valley in between with few galaxies
C) a continuum from faint,blue galaxies to bright,red galaxies
D) a continuum from faint,red galaxies to bright,blue galaxies
E) a main sequence,just as for stars