Complex sentence: The remaining portion choose either the "Some Other Race" category or the "Two or More Races" category on the 2010 census, many of these people are racially mixed, mainly of Mulattos and Triracials.
Split into simpler sentences: The remaining portion choose either the "Some Other Race" category or the "Two or More Races" category on the 2010 census. Many of these people are racially mixed, mainly of Mulattos and Triracials.