Agroup of student researchers divide up the different times and buildings on their campus to attempt to observe when people will hold a door open for another person. these student researchers are most likely to use which research method design when conducting their study?

The answer is "Naturalistic observation design".

Naturalistic observation happens in reality, instead of in a research center. This is the means by which one can most viably evaluate practices without impacting them.  

Naturalistic observation is an research strategy generally utilized by therapists and other social researchers. This procedure includes watching subjects in their common habitat. This kind of research is frequently used in circumstances where directing lab inquire about is improbable, taken a toll restrictive or would unduly influence the subject's behavior.

answer; /// i do believe that the above is (true)

there are so many examples for that in different areas, like biology experiment carried out in our lab recently.

here's one link :