Which are true of the diathesis-stress model of mental illness?Please identify all correct answers. 1: When an enduring vulnerability factor in a person is coupled with a recent stressor, it results in psychological disorder. 2: Only one of the diathesis or stressor needs to be present for symptoms of the psychological disorder to occur. 3: Both the diathesis and the stressor must be present to lead the symptoms of the psychological disorder. 4: Diathesis and stressors have specific definitions.