Question: How do the concepts of race and ethnicity differ? Need Assignment Help? a. Ethnic identities, but not racial identities, reflect perceptions about biological traits. b. Ethnic identities focus on cultural traits and are sometimes voluntary, whereas racial identities do not. c. Ethnic identities are measured by the U.S. Census Bureau, but racial identities are not measured. d. Ethnic identities cannot change over the course of a lifetime the way racial identities can.