Final answer:
The dimensional approach allows an understanding of how abnormal behavior varies in severity over time and how behaviors change from one disorder to another.
Step-by-step explanation:
The approach that would allow an understanding of how abnormal behavior varies in severity over time and how behaviors change from one disorder to another is the dimensional approach. Unlike the categorical approach, which classifies behavior into distinct categories, the dimensional approach considers behavior as existing on a continuum. This approach recognizes that abnormal behavior can vary in severity and can transition between different disorders.