Final answer:
The question is about identifying pairs of variables, such as the number of participants and the year, in a statistical study related to Fall League Soccer.
Step-by-step explanation:
The subject in question appears to be Mathematics, specifically related to statistics or data analysis. This is evident from the context of the question asking about variables such as '# of Participants' and 'Fall League Soccer', which are likely to be data points in a statistical study or data set. The question seems to pertain to identifying which variables might be used to create a chart or a graph, such as a scatter plot or a line graph, to analyze the relationship between two variables, like the number of participants and the year for the Fall League Soccer.