Dr. X wishes to study how college students interact in the student union. Which research method should he use

naturalistic observation

Explanation:

Naturalistic observation: In psychological research, the term "naturalistic observation" is determined as a specific research method whereby different individuals or participants are being observed or noticed in their "natural setting". Generally, social scientists and psychologists utilize naturalistic observation to study particular cultural & social setting that couldn't be looking into or investigated by other means, like, hospitals, prisons, etc.

In the question above, Dr X should use naturalistic observation.

in this scenario it would be the consumer demand as most influential in making the decision. the band members need to figure out where and from whom they will make the most money, in other words who out of the two consumer groups - football fans or car drivers - will spend their money, who is more likely to contribute to their cause and buy what they are offering.