Cheryl wants to find the number of hours seventh-graders do homework each week. there are 297 girls and boys in seventh grade. which is the best way for cheryl to get a representative sample without spending too much time? a.) she can survey 15 of her friends in the school. b.) she can survey every sixth-grade student in the school. c.) she can randomly survey 50 girls in the entire school. d.) she can randomly survey 50 seventh-graders in the school.