a(
stratified sample
convenience sample
systematic sample
simple random sample
cluster sample
is obtained by dividing the population into groups and selecting all individuals from within a random sample of the groups.

cluster sample

Explanation:

Cluster sampling is used in statistics with the natural population. the population is divided into subgroups and then through random sampling researcher selects a random sample from the subgroups of the population. This sampling has been used in market researcher When the researcher does not get the information as a whole. Suppose a person wants to know about the taxes in the city, the researcher selects the cities and collect data from that city and implement that data on the whole population. It is more practical and more reliable then stratified and simple random sampling. In this sampling, the data should be heterogeneous. each cluster of the population should be the representation of the whole population.  

It is of two types:

answer; i believe it was by president pranab mukherjee or by the chief justice of kerala high court; ///plz check luck

sounds good to me mate!