Step 1: Pathology is the branch of medicine that studies the causes and effects of disease, especially through laboratory examination of body tissues and fluids for diagnostic or forensic purposes.
Step 2: The word derives from the Greek roots - 'pathos' meaning suffering or disease, and the suffix relating to study or reasoning. In the descriptive sense intended here, pathology is the term for the way a disease works.
Step 3: Among the given options, 'Work' best captures this idea, since pathology describes the workings or mechanism by which a disease operates.
Step 4: Function, Details and Explains do not correspond to the standard definition of the term, so the correct answer is Work.