What are antibodies primarily responsible for?

Antibodies are proteins produced by the immune system that play a crucial role in identifying and neutralizing pathogens such as bacteria and viruses. Their primary function is to bind to specific antigens on these pathogens, marking them for destruction by other immune cells or neutralizing them directly. This process is essential for the body’s immune response, allowing it to effectively fight off infections and prevent disease.

The other functions listed in the options do not pertain to the role of antibodies. Transporting oxygen is primarily the function of hemoglobin in red blood cells. The breakdown of carbohydrates involves digestive enzymes and metabolic processes, not antibodies. Regulating blood sugar levels is managed by hormones such as insulin and glucagon, not by antibodies. Therefore, the primary responsibility of antibodies is indeed to fight off infections, supporting the body's defense mechanisms.