Question

the population of a town is divided into three age categories. a random sample of each category is surveyed about voting choices. this type of sampling is called
cluster sampling.
stratified sampling.
simple random sampling.
systematic random sampling

Explanation:

Stratified sampling divides the population into subgroups (strata) based on certain characteristics (here age - categories) and then samples from each subgroup. This is what's described in the problem.

Answer:

B. stratified sampling