What is the type of research method that focuses on the relationship between physiological processes and behavior?

The research method is known as psychophysiological.

Explanation: Psychophysiology is a branch of physiology that deals with the interaction between the mind(psyche) and physiological processes (body).

This study research how the mind and body respond in relation their activities.

An example of this is the fact when an individual is stressed(body) thinking (mind) can make the stress significantly worse.

Or overthinking (mind) can cause an individual to have high blood pressure (body). The relationship between these interactions is termed Psychophysiology.

"social stratification refers to the way people are ranked and ordered in society. in western societies, stratification is primarily seen and understood as a result of socioeconomic status, which produces a hierarchy in which access to resources, and possession of them, increases from the lower to the upper strata"