To measure achievement of third grade students, a school system randomly selects four third grade classes and tests all children in those classes. This is an example of what type of sampling? a. systematic
b. stratified
c. cluster
d. convenience

Cluster

Step-by-step explanation:

When observations from a large population are divided into groups, such that subjects in each of these groups are similar to one another than those in the other groups. These individual groups of observation are called clusters. In the scenario above, the random group of 4 third grade classes selected represent of cluster or group since all the subjects belong to the class grade which is to be measured and all subjects belonging to the selected cluster or group are to be measured.

mental cunning

explanation:

he is often referred to as a man of twists and turns