What is the difference between race and ethnicity?

While race and ethnicity share an ideology of common ancestry, they differ in several ways. First of all, race is primarily unitary. You can only have one race, while you can claim multiple ethnic affiliations. You can identify ethnically as Irish and Polish, but you have to be essentially either black or white.

Race is black, white, mexican etc. Ethnicity is like African, Spanish, Polish, etc

My answer is letter d