The study of all features of the body's second and third lines of defense is known as:

• A. Pathology
• B. Immunology
• C. Hematology
• D. Microbiology

Answer: (B)

Verified step by step guidance

1. Step 1: Begin by understanding the key terms in the question. The 'second and third lines of defense' refer to the body's immune system mechanisms beyond the initial physical and chemical barriers (like skin and mucous membranes). These include innate immune responses (second line) and adaptive immune responses (third line).
2. Step 2: Define the term 'Immunology.' Immunology is the branch of science that studies the immune system, including its components, functions, and disorders. It specifically focuses on how the body defends itself against pathogens and other harmful agents.
3. Step 3: Compare the other options provided in the question: 'Pathology' is the study of diseases and their effects on the body, 'Hematology' is the study of blood and its disorders, and 'Microbiology' is the study of microorganisms. None of these directly focus on the immune system's defense mechanisms.
4. Step 4: Relate the concept of the immune system's second and third lines of defense to Immunology. The second line includes processes like inflammation and phagocytosis, while the third line involves specific immune responses such as antibody production and T-cell activation. These are central topics in Immunology.
5. Step 5: Conclude that the study of the body's second and third lines of defense aligns most closely with Immunology, as it encompasses the mechanisms and responses involved in protecting the body from pathogens.