Answer: Abnormal psychology
Step-by-step explanation:
Abnormal psychology is defined as the study of abnormal behavior, thoughts ,emotion and believes of an individual .This behavior is noticed because the pattern followed by people is different than the standard norm and thus fail to function normally.
The deviated functioning of a person can be considered as the psychological disorder .This situation can be cured through emotional disorder and mental disorder treatment.
According to the situation mentioned in question, Kelly should study the field of abnormal psychology to gain information about disorder in psychological field and restoration of health mental functioning.