Which study observes behaviour without applying any treatment?

• A. Designed experiment
• B. Case study
• C. Observational study
• D. Cross-sectional study

Answer: (C)

Observational study means watching behaviour as it occurs, with no treatment or intervention applied. The researcher simply records what happens in the natural setting, so there’s no random assignment or manipulation of variables. This contrasts with a designed experiment, where researchers deliberately give or withhold a treatment to different groups to see its effect. A case study examines a single person, group, or situation in depth and may use various data collection methods, but its defining feature isn’t about withholding treatment. A cross-sectional study is an observational design that collects data at one point in time, giving a snapshot, but it’s still observation rather than manipulation. Because the scenario focuses on observing behaviour without altering conditions, the best match is an observational study.