(C) Case study: A case study is a research method that involves an intensive, in-depth investigation of a single individual, group, or phenomenon. It uses multiple sources of information—like interviews, observations, and school records—to build a detailed and holistic picture of the subject. When applied to a student, it allows educators and researchers to understand the student's background, academic performance, behavior, and social-emotional development in great detail, making it the ideal method for a thorough, in-depth analysis.