The correct option is C vaccine
A vaccine is composed of weakened or dead microbes which are introduced into a healthy individual's body. The dead or weakened pathogen stimulates the production of antibodies against that specific pathogen which was injected. Vaccines can be injected or administered orally.
Antibiotics are medicines (such as penicillin) used to treat patients who are mostly infected by a bacteria.
Antigen is any foreign substance entering the body, like pathogens, dust, pollen, snake venom, etc that evokes an immune response.