Final answer:
Immunology (option A) is the study of the body's immune system and its defenses against pathogens, which includes innate barriers like skin and mucous membranes and adaptive responses with antibodies and memory cells.
Step-by-step explanation:
The study of the body's defenses against pathogens is immunology. This scientific field explores how the immune system works to protect us from diseases caused by pathogens such as bacteria, viruses, and other microorganisms. Immunology encompasses understanding both the innate and adaptive immune responses. The innate response refers to the immediate, non-specific defense mechanisms that act against a wide range of pathogens, including mechanical, chemical, and biological barriers such as skin, mucous membranes, and beneficial bacteria, respectively.
The adaptive immune response involves the production of antibodies and memory cells that provide long-term immunity by recognizing and neutralizing specific pathogens. B Cells and T Cells are central to this process, helping the body to remember and more efficiently attack pathogens they have encountered previously. The immune system is astonishing in its complexity and its ability to adapt and defend against a myriad of infectious agents.