In order to understand what factors cause mental disorders, most psychologists use a:

biopsychosocial assessment

Explanation:

A biopsychosocial assessment is an assessment by psychologists to understand which factors cause mental disorders in an individual. This evaluation consists of a series of questions that evaluate not only the mental quality of the individual, but also the physical quality, being able to inform which mental disorders the individual has been feeling and consequently the best way to treat them.

i believe it is the last one. im sorry if im wrong!

the trait of personality falls in the middle of the diagram because personality is a mixture of ones nature and environment.