Which of the following is an example of descriptive research?

Descriptive research is primarily aimed at providing a detailed account of a phenomenon rather than manipulating or controlling variables. Observational studies exemplify this approach as they focus on documenting and describing characteristics or behaviors in a natural setting without intervention by the researcher. This type of study helps to generate hypotheses and understand patterns or trends within a population.

In contrast, randomized controlled trials involve the manipulation of variables to test the efficacy of an intervention, making them a form of experimental research rather than descriptive. Case studies, while they provide in-depth insights into individual cases or phenomena, are often used to explore specific instances in detail, and although they are descriptive in nature, they do not encompass the broader observational approach. Longitudinal studies track the same subjects over time to observe changes and developments, often involving some level of intervention or hypothesizing, which distinguishes them from purely observational descriptive methods. Thus, observational studies stand out as a clear example of descriptive research.