The counseling department of a small college wants to interview a sample of 200 students about various aspects of their college experience. The registrar's office sends them a list of all 5000 students in alphabetical order. The students are divided into 24 different categories according to major, classification, gender, and national origin. A proportionate number from each group was sampled. What type of sampling was used?

A. cluster
B. random
C. stratified