Which of these is would be best classified as an ethnic group

According to some historians which marks at the beginning of the us civil war

How many categories of information are there

Select all that apply. if you lived in the olmec civilization you might have: 1) been amoung the first people on the planet to eat corn 2)worshiped a cougar deity 3)seen sculptures with downturned mouths and eyes 4)visited pyramids on a coastal island 5) made small figurines to put in trenches around the local temple