What is a primary function of antibodies?

Antibodies play a crucial role in the immune system primarily by binding to and neutralizing pathogens, such as bacteria and viruses. This binding mechanism helps to mark these invaders for destruction by other immune cells or directly neutralizes their harmful effects. Each antibody is specific to a particular antigen, which allows for targeted immune responses. This ability to identify and latch onto pathogens is vital for preventing infections and supporting the body's defense mechanisms.

In contrast, the other options describe functions that are not related to antibodies. For instance, transporting oxygen in the blood is primarily the function of hemoglobin in red blood cells. The formation of cell membranes involves phospholipids and proteins, not antibodies. Metabolism is a collection of biochemical processes that involves enzymes but does not relate to the actions of antibodies directly. Thus, binding and neutralizing pathogens is the specific and primary function of antibodies within the immune response.