### **Core Concept**
Membrane filtration is a method used to sterilize heat-labile solutions by passing the solution through a membrane with pores small enough to trap microorganisms, thereby rendering the solution sterile.

### **Why the Correct Answer is Right**
Membrane filtration is the preferred method for sterilizing heat-labile solutions because it does not involve the application of heat, which can denature proteins or degrade sensitive molecules. This method is particularly useful for solutions that contain enzymes, antibodies, or other labile components that are sensitive to high temperatures. The membrane filter has pores of an exact size that allows water and small molecules to pass through while retaining bacteria, viruses, and other microorganisms.

### **Why Each Wrong Option is Incorrect**
* **Option A:** Dry heat is a suitable method for sterilizing equipment and materials that can withstand high temperatures, but it is not suitable for heat-labile solutions as it can cause denaturation of proteins and degradation of sensitive molecules.
* **Option B:** Autoclaving involves the use of high-pressure steam, which can also cause denaturation of proteins and degradation of sensitive molecules, making it unsuitable for heat-labile solutions.
* **Option D:** Pasteurization involves heating a solution to a temperature that is sufficient to kill most microorganisms, but not hot enough to denature proteins or degrade sensitive molecules. However, it is not as effective as membrane filtration in sterilizing solutions that contain a high concentration of microorganisms.

### **Clinical Pearl / High-Yield Fact**
When working with heat-labile solutions, it's essential to use aseptic techniques and to handle the solutions gently to prevent contamination. Additionally, it's crucial to verify the sterility of the solution using a sterility test, such as the membrane filtration method, to ensure that the solution is free from microorganisms.

### **Correct Answer:**
✓ Correct Answer: C. Membrane filtration