What historical contribution is Paul Ehrlich credited with in antimicrobial development?

• A. Creating the first synthetic broad-spectrum antifungal used widely in hospitals during the 1920s
• B. Discovering penicillin from a mold contaminant in a Petri plate and proving it cured bacterial infections
• C. Proposing the "magic bullet" concept and developing an early chemotherapeutic agent to treat syphilis
• D. Showing that viruses could be selectively killed with metal salts without host damage

Answer: (C)