C. can base his claim on discrimination based on color and/or race if Ms. Scales, while also black, is of different ethnicity.
Well, a person of black color can sue another black colored person for discrimination, so it takes out option A, B and E.
The use of word “and/or” is of immense importance here and must be noted because it is the difference between option C and D.
While option D means either can be based on color or race but option C is correct since it can be because of race and/or color. The use of word “different ethnicity” must also be noted for discrimination based on race.