## **Core Concept**
Sterilization of culture media, especially those containing serum, requires a method that effectively kills microorganisms without damaging the heat-sensitive components of the media. Serum-containing media are commonly used in cell culture for growing cells.

## **Why the Correct Answer is Right**
The correct answer, **.**, refers to filtration sterilization. This method is particularly suitable for heat-sensitive materials, such as serum or culture media containing serum, that cannot withstand the high temperatures used in autoclaving. Filtration involves passing the medium through a filter with pores small enough to block bacteria and other microorganisms, effectively sterilizing the medium without exposing it to heat.

## **Why Each Wrong Option is Incorrect**
- **Option A:** Autoclaving involves high-pressure steam and is effective for many types of media but can denature or coagulate serum and other heat-sensitive materials, making it unsuitable for serum-containing media.
- **Option B:** and **Option D:** These options are not standard methods for sterilizing culture media containing serum.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that for materials that are heat-sensitive, such as serum, filtration is a critical method for sterilization. This ensures that the integrity of the serum is maintained, which is crucial for supporting cell growth in culture.

## **Correct Answer:** . Filtration.