AP Psychology Practice Test 2026 - Free AP Psychology Practice Questions and Study Guide

The correct answer is established as all cases in a group from which samples may be drawn because a population in research refers to the complete set of individuals or items that share a common characteristic relevant to a study. This definition encompasses everyone or everything that falls within the criteria of interest for the research, which could later inform findings about a larger group based on collected data from that population.

Other options describe components of research but do not accurately define population. A single case study subject would not represent the entire population and is rather a unit of study within that population. A random sample for survey distribution refers to a subset of the population used for the purpose of making inferences about the whole but does not itself define the population. The total number of surveys completed indicates participation or engagement in a study but does not encompass the broader group from which those responses might be drawn.