Which term means the study of the causes of disease?

• A. Pathology
• B. Etiology
• C. Nosology
• D. Physiology

Answer: (B)

The term that focuses on why a disease occurs is etiology. Etiology deals with the cause or origin of a disease, including infectious agents, genetics, environmental factors, or other contributors. This distinguishes it from pathology, which studies the tissue and organ changes that occur with disease; nosology, which is about classifying diseases; and physiology, which examines how normal body systems function. For example, understanding why pneumonia happens means looking at its etiologies—bacteria, viruses, or other irritants—rather than just observing tissue damage, classifying the disease, or describing normal respiratory function.