A researcher wants to obtain a sample of 25 teachers from a school district employing 400 teachers in 8 schools. Choose the BEST method for doing this.
A) Select the teachers whose students have the highest grade point averages in the system.
B) Ask the principal of each school to choose 3 teachers, then select the 25th teacher randomly.
C) Randomly select 12 male teachers, 12 females, and then randomly select a 25th teacher of either sex.
D) From an alphabetized list, select a teacher randomly, then select every 16th teacher on the list until 25