Answer:
stratified random
Step-by-step explanation:
Sampling is a technique used in inferential statistics to used to collect a sample which is an accurate representation of the population from which the sample is chosen.
In stratified sampling the population is put in groups according to a criteria. Then from these groups a member is chosen at random where each group has equal representation in the group.
Here, the group are classified by social class and age and people are selected randomly from these groups. Hence this technique is called stratified random sampling.