Answer: a) Diathesis-stress
Explanation: Diathesis stress is the theory of psychology that determines that disorder or severe degradation of body and mind that can occur due to coming in contact with life experiences and situations that makes the person prone towards stress or mental disturbance.
Mistee's situation can be explained by diathesis stress theory in the field of psychopathology due to the stressing job that is making her depress.
Other options are incorrect because biological approach consist of looking at physical issues. Humanistic approach is based of inducing goodness in people.Psycho-dynamic approach is the psychological method of determining the personality-building of human.
Thus, the correct option is option(a).