Which scenario is an example of naturalistic observation?

Naturalistic observation involves studying subjects in their natural environment without any manipulation or intervention by the observer. In the scenario where children who already play violent video games are observed, the focus is on their natural behaviors and interactions as they engage with the video games in their typical settings. This allows researchers to gather data that reflects genuine behavior in a real-world context, rather than in a contrived or controlled situation.

The other scenarios involve some form of manipulation or structured data collection. Changing dietary habits in a controlled group suggests an experimental setup where variables are managed to observe specific outcomes. Conducting a survey indicates a structured approach to gathering self-reported data, which doesn't capture spontaneous behavior in a natural setting. Testing the effects of video games in a laboratory context involves a controlled environment, which contrasts with the essence of naturalistic observation.