Nicholas has been diagnosed with depression, borderline personality disorder, and a phobia of social interactions. since nicholas has multiple mental disorders at once, we would say that a high exists in his case.

The correct answer is :

Comorbidity

Explanation:

Comorbidity is the term used to refer the medical cases in which several clinical conditions affect the patient. Sometimes, it happens that there is a primary condition that has an effect to unchain the others as complication of the entire system. For example, a patient with diabetes could develop also a coronary artery disease in the evolution of the condition. Another case could be when a patient is diagnosed with depression and this can cause also anxiety episodes.  

this null effect is caused by a weak manipulation and ineffective internal validity. in a scientific study, as the one dr. morimoto is trying to perfom, internal validity refers to the confidence placed in the cause-effect relationship and to how well an experiment is done and able to eliminate confounding variables.