Answer: Cluster sampling
Step-by-step explanation:
A cluster sampling is a kind of random sampling technique in which the researcher splits the whole population into distinct sets known as clusters.
After that, he choose a random sample of clusters from the population and do analysis on it.
In the given situation, the objective of survey : "To determine customer opinion of their pricing:".
He first divides the number of check out lines according to weeks and randomly selects 140 check out lines during a certain week and surveys all customers in the check out lines. .
(Here , check out lines = clusters )
Therefore , the type of sampling is used = Cluster sampling
