Which of the following best describes a case study?

A case study is characterized as an intensive exploration or examination of a particular individual, group, organization, or community. This approach allows for a deep understanding of various factors affecting the subject being studied, including contextual and environmental variables. In essence, it provides rich qualitative insights that can help to develop theories or understand complex phenomena.

The reason why this definition fits a case study is that it focuses on in-depth analysis rather than breadth. By concentrating on a specific entity, researchers can gather detailed information, often utilizing various methods such as interviews, observations, and document reviews, to achieve a comprehensive understanding of the subject matter.

In contrast, the other options outlined do not align with what defines a case study. A large-scale survey targets broad populations and quantifies data, which is fundamentally dissimilar to the detailed qualitative analysis of a case study. A randomized trial is designed to test the efficacy of a new intervention under controlled conditions, focusing more on establishing cause-and-effect rather than in-depth exploration. Lastly, a systematic review involves collecting and analyzing a large body of existing research on a topic, which serves to summarize findings rather than provide an in-depth examination of a specific case. Thus, the option describing a case study as an intensive study of a specific group or community