Which term is defined as 'A protein that acts against a specific antigen/ protects the body from antigens'?

• A. ascites
• B. anticoagulant
• C. antigen
• D. antibody

Answer: (D)

Antibodies are the immune system proteins that act against a specific antigen to protect the body from pathogens. They’re produced by B cells in response to an antigen and have a unique binding site that matches a particular antigen. When an antibody binds its antigen, it can neutralize the threat directly, mark it for attack by other immune cells, or activate the complement system to destroy the invader. This targeted action is what makes antibodies effective at defending the body. An antigen is the substance that triggers the immune response, not the protective protein itself. Ascites is fluid buildup in the abdomen, and an anticoagulant prevents blood clotting.