Which of the following describes a function of antibodies?

Antibodies are specialized proteins produced by the immune system that play a crucial role in identifying and neutralizing foreign substances, such as pathogens (bacteria, viruses, and toxins). The primary function of antibodies is to bind to specific antigens, which are unique molecules found on the surface of pathogens. This binding marks the pathogen for destruction or neutralization and helps facilitate its removal from the body.

When an antibody binds to an antigen, it can block the pathogen's ability to infect cells, enhance the effectiveness of other immune cells, and activate other components of the immune system, such as the complement system. This function of binding is critical in helping the body mount an effective immune response and is foundational for the adaptive immune system.

Other options describe important aspects of the immune response but do not accurately represent the central function of antibodies. For example, while antibodies can play a role in triggering inflammation or stimulating T cells indirectly, their primary and most direct role is to bind with antigens. Killing pathogens directly is typically carried out by other immune components rather than antibodies themselves.