Fifteen Freshmen, 15 Sophomores, 15 Juniors, and 15 Seniors of a University

Multiple Choice

Fifteen freshmen, 15 sophomores, 15 juniors, and 15 seniors of a university were surveyed to study the sleeping habits of college students throughout their college years.The best description of the sampling method used is

A) systematic random sampling
B) stratified random sampling
C) judgment sampling
D) simple random sampling
E) cluster random sampling