Chocolate Chippers wants to see if their new chocolate bar is enjoyed more by high school or middle school students. They decide to visit one middle school and one high school in Atlanta, GA. After interviewing the students at each school, they determine that middle school students like their chocolate more than the high school students do. What is the sample of the population?

All students who attend middle school or high school in the country
All students who attend middle school or high school in Atlanta, GA
All students who attend one middle school and one high school in Atlanta, GA
All students who attend middle school or high school in Georgia