Answer:
A. Choosing the third person listed on every fifth page of the phone book is stratified sampling.
Explanation:
Stratified sampling involves grouping the population into subgroups before sampling. It provides a more manageable and cheaper means of sampling data by placing the population into grouped strata. The only problem is that this sampling method cannot be used in a data population that cannot be stratified. In this question, the phone book is stratified into subgroups of every five pages, and the third person listed is chosen to represent the subgroup