What is the study of the nature and cause of disease, including changes in structure and function?

The correct answer is the study of pathology, which focuses on understanding the nature and causes of diseases, as well as the associated changes that occur in the structure and function of cells, tissues, and organs. Pathology provides insights into how diseases develop, progress, and affect the body, which is crucial for diagnosis and treatment.

This field encompasses both the microscopic examination of tissues (histopathology) to identify disease changes at a cellular level and the broader epidemiological and clinical aspects that explain disease processes. Understanding pathology is foundational for healthcare professionals, including those in mortuary sciences, as it informs the investigation of causes of death and the processes that lead to various health conditions.

In contrast, physiology focuses primarily on the functions of living organisms and their parts, while anatomy deals with the structure of organisms. Histology is a closer subfield that studies tissues at a microscopic level but doesn't encompass the overall study of disease.