An elementary school has the following students. 240 students in 3rd grade

150 students in 4th grade

100 students in 5th grade

The librarian wants to know which books are most popular among the school’s 3rd-5th grade students. Which of the following sampling methods would provide the most accurate representation of the populations’ preferences?

Select 15 third graders, 15 fourth graders and 15 fifth graders at random

Select 15 third graders, 25 fourth graders and 40 fifth graders at random

Select 40 third graders, 25 fourth graders and 15 fifth graders at random

Select 40 third graders, 40 fourth graders and 40 fifth graders at random