A sample chosen by stratified random sampling involves a. randomly selecting one of the first k elements in an ordered population and then selecting every kth element in the population thereafter. b. a sample chosen by a knowledgeable person on the subject of the study. c. selecting a simple random sample of clusters from the available clusters in the population. d. selecting a simple random sample from each of a given number of strata formed from the elements in the population.

The answer is (d) = Selecting a simple random sample from each of a given number of strata formed from the elements in the population.

Stratified random sampling is a sampling method where the population has a number of distinct categories. The population can be organized into separate strata and each stratum is then sampled as an independent sub-population out of which individual elements can be randomly selected. In this case, each unit in a stratum, that is, each element in a group has the chance of being selected into the sample and there is adequate representation of minority sub-groups. With Stratified sampling, the best result occurs when elements within strata are internally homogeneous.