The University Registrar Mailed a Survey to a Total of 400

Multiple Choice

The University Registrar mailed a survey to a total of 400 students.The sample included 100 students randomly selected from each of the first-year,second-year,third-year,and honours level students on campus last term.What sampling method was used?

A) Simple random sample.
B) Systematic sample.
C) Stratified sample.
D) Cluster sample.