Which of the following best describes a case study?

A case study is defined as a deep investigation of a single individual or group, making this option the most accurate description. This research method is often employed in sociology to gather comprehensive and detailed information about complex social phenomena, behaviors, or experiences within a specific context. The emphasis is on acquiring in-depth knowledge, which can lead to meaningful insights that might not be achievable through broader quantitative research methods.

The case study method allows researchers to explore particularities and nuances, providing a richer understanding of the subject matter. This depth of analysis often reveals the underlying causes, motivations, and factors influencing the subject being studied, whether that be an individual, a group of individuals, an organization, or a community. Thus, it is particularly useful in fields like sociology, psychology, and education, where understanding context and depth is crucial.

Other options describe different types of research approaches. While extensive analyses involving multiple groups are characteristic of comparative or cross-sectional studies, brief overviews of common behaviors suggest a survey or correlational study rather than a case study's depth. Additionally, a comparative study of different research methods does not reflect the essence of a case study, as it focuses on methodological comparison rather than detailed exploration of a singular case.