What is the primary function of antibodies?

The primary function of antibodies is to destroy pathogens. Antibodies, also known as immunoglobulins, are specialized proteins produced by B cells in response to specific antigens, which are unique molecules found on the surface of pathogens like bacteria and viruses. When antibodies bind to these antigens, they neutralize the pathogen directly, preventing it from infecting cells, and also mark it for destruction by other components of the immune system, such as phagocytes.

Additionally, antibodies can enhance phagocytosis, a process where immune cells engulf and digest pathogens, and they can activate the complement system, which contributes to the destruction of pathogens. This multi-faceted role of antibodies in targeting and eliminating pathogens is essential for the immune system's ability to protect the body from infections and diseases.

In contrast, the other options do not accurately reflect the primary role of antibodies. While some immune system components do regulate immune responses or play a role in cell replacement, these functions do not specifically define what antibodies do. The transportation of oxygen is a function of hemoglobin in red blood cells, not antibodies. Thus, the distinctive and critical role antibodies play in pathogen destruction is fundamental to their function within the immune response.