If researchers wanted to examine the opinions of people listed in a city directory, they might call every tenth or fiftieth or hundredth name listed. this would constitute

A simple random sample

Explanation:

A simple random sample is a type of sampling in which everyone stand equal chance to be chosen.

This is done so that unbiased sample can be obtained where everyone stand an equal chance to be represented.

In a large population each participant is randomly picked and all based on chance no specifical procedure followed.

answer; depression and breathing related sleep disorder(independent);