Answer:
C. The principal randomly selects homeroom classes and surveys each student in the chosen classes.
Step-by-step explanation:
Middle school is 6-8th. Surveying only the eighth-grade students won't give a representative sample of the whole school only the eighth-graders. Option A is incorrect.
Surveying only the students in detention represents a very small amount of students compared to the school, therefore it is not a representative sample. Option B is incorrect.
Yet again, the students in the math club is a small amount of students compared to the school. It does not represent the entire, or majority of the population. Option D is incorrect.
Picking students from homeroom classes and surveying each will give a wider variation of opinions from each grade and therefore a representative sample. Option C is the correct answer.