Which of the following correctly matches the terms antigen, artificial active immunity, and zoonosis with their definitions?

• A. Antigen: molecule recognized by immune system; Artificial active immunity: immunity generated by deliberate antigen exposure (e.g., vaccination); Zoonosis: disease naturally transmitted between animals and humans
• B. Antigen: any cell that causes disease symptoms; Artificial active immunity: passive transfer of immune cells from another person; Zoonosis: a disease limited to a single animal species with no human transmission
• C. Antigen: a vaccine adjuvant component; Artificial active immunity: natural immunity gained after infection; Zoonosis: a pathogen that jumps species but only causes mild disease in humans
• D. Antigen: an antibody that neutralizes pathogens; Artificial active immunity: the process of administering antibiotics to prevent infection; Zoonosis: viruses that only infect humans and not animals

Answer: (A)