## Core Concept
Vaccines are biological preparations that provide active acquired immunity to a particular infectious disease. The sterilization of vaccines is crucial to eliminate any microbial contamination that could cause infection. Various methods can be used for sterilization, but the choice of method depends on the type of vaccine and its components.

## Why the Correct Answer is Right
The correct answer, , involves the use of **gamma radiation** or **ethylene oxide** for sterilizing vaccines, but most commonly, **filtration** is utilized. Filtration, especially through **0.2-micron filters**, is widely used for heat-sensitive materials, including vaccines, to remove bacteria and other microorganisms without denaturing the vaccine components. This method is preferred for vaccines because it effectively removes contaminants without damaging the vaccine's immunogenic properties.

## Why Each Wrong Option is Incorrect
* **Option A:** - This option is incorrect because **autoclaving** involves high pressure and temperature, which can denature proteins and destroy the immunogenic properties of vaccines.
* **Option B:** - This option is incorrect as **pasteurization** involves heating liquids to a lower temperature than boiling point for a certain period, which might not be sufficient to eliminate all microbial contaminants and could also potentially damage vaccine components.
* **Option D:** - This option is incorrect because **UV radiation** might not penetrate deeply enough to sterilize the entire vaccine material uniformly and could also potentially damage the vaccine components.

## Clinical Pearl / High-Yield Fact
A key point to remember is that vaccine sterilization must ensure the removal or killing of pathogens without compromising the vaccine's efficacy. Filtration is a commonly used method for vaccine sterilization due to its gentleness on biological materials.

## Correct Answer Line
**Correct Answer: C. **