Answer:
1. Stratified Random Sampling
Step-by-step explanation:
Sampling is a technique of drawing small number of representative units from population.
Stratified Random Sampling is when population is divided into : heterogenous (different) groups, homogeneous (identical) within themselves - known as Strata.
Process of drawing Sample from each such strata group is called Stratified Random Sampling. This sampling makes sample better representative of various groups in population. Eg : Dividing population in strata based on gender , religion etc & then drawing sample from each strata.
Researcher dividing students into - freshman, sophomores & other groups ; then drawing sample from each group is an example of Stratified Sampling. It creates representative sample of each student body in school .