Step 1: Understanding the Concept:
"Pyretic" refers to fever, and "anti" means against, so an antipyretic works against fever.
Step 2: Detailed Explanation:
Paracetamol is a typical antipyretic. It lowers the body temperature in fever.
Step 3: Why the other options are wrong.
Killing microorganisms is the job of antibiotics, antiseptics or disinfectants. Pain relief is done by analgesics. Preventing pregnancy is done by antifertility drugs.
Final Answer:
Antipyretic drugs reduce fever, option (C).
\[ \boxed{\text{Reduce fever}} \]