Answer :
Final answer:
Stratified sampling is used by the market researcher to survey residents by age categories.
Explanation:
Stratified sampling is used in this scenario. The market researcher has divided the residents of a region into age categories and is surveying 45 people from each category, making it a clear example of stratified sampling. This method involves dividing the population into subgroups or strata and then selecting samples from each subgroup.
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