Which of the Following Would MOST Clearly Demonstrate a Functional

Which of the following would MOST clearly demonstrate a functional relationship?

A) Conduct narrative recordings in various settings. Then compile a sequence analysis.
B) Directly observe environmental events and target behaviors as they normally occur in an unobtrusive manner, in the natural environment.
C) Execute repeated rapid alternations between different environmental conditions. Collect and graph data.
D) Use a scatterplot to both collect and graph data. When sufficient baseline data have been collected, complete a pattern analysis.