Answer:
Randomly select 12 students from each grade level and ask whether they drive to school.
Explanation:
1/3: Both methods are random, but only one method gives Nayara an equal chance of surveying every student within a grade level.
2 / 3: If Nayara selects students who drive to school, she has no chance of selecting students in the grade level who do not drive to school.
3 / 3 The valid method: Randomly select 12 students from each grade level and ask whether they drive to school.