The Difference Between a Cluster Sample and a Stratified Random

Multiple Choice

The difference between a cluster sample and a stratified random sample is:

A) Cluster samples study all possible clusters;stratified random samples randomly select strata
B) Cluster samples use oversampling;stratified random samples use undersampling
C) Cluster samples use randomly selected clusters;stratified random samples use pre-determined strata
D) There is no difference between them