A public health researcher wants to study the prevalence of a certain disease in a large city. To ensure they have a representa tive sample, they divide the city into different regions based on socioecono mic status (low.middle, and high income ). Then, they randomly select a proportional number of individuals from each socioeconomic group to participate in the study. Which type of sampling technique is being used in this scenario? a. Simple Random Sampling b. Stratified Sampling c. Cluster Sampling d . Systematic Sampling

The correct answer is b. Stratified Sampling.<br /><br />In this scenario, the researcher is dividing the city into different regions based on socioeconomic status (low, middle, and high income). This is known as stratification. Then, they are randomly selecting a proportional number of individuals from each socioeconomic group to participate in the study. This is the key characteristic of stratified sampling, where the population is divided into subgroups (strata) and a sample is taken from each subgroup. This ensures that each subgroup is adequately represented in the sample, making it a representative sample of the entire population.