**Core Concept**
Autoclaving is the most widely used and effective method of sterilization by heat, utilizing steam under pressure to kill microorganisms and spores. This process is critical in medical settings to prevent the spread of infection.

**Why the Correct Answer is Right**
Autoclaving works by creating a high-temperature, high-pressure environment that inactivates enzymes, disrupts cell membranes, and ultimately kills microorganisms. The steam penetrates deeply into materials and can reach temperatures of up to 121°C, effectively killing all forms of microbial life, including bacterial spores. This method is particularly effective because it can penetrate porous materials and is capable of killing a wide range of microorganisms.

**Why Each Wrong Option is Incorrect**
**Option A:** Dry heat sterilization is less effective and slower than autoclaving, making it less suitable for laboratory and medical settings.
**Option B:** Boiling water is not sufficient to kill all forms of microbial life, particularly bacterial spores, which can survive temperatures up to 100°C.
**Option C:** Ethylene oxide gas sterilization is a chemical method that is effective for heat-sensitive materials but is not as widely used as autoclaving.

**Clinical Pearl / High-Yield Fact**
Autoclaving is a critical component of infection control in medical settings, and its effectiveness can be compromised if the equipment is not properly maintained or if the process is not followed correctly.

**Correct Answer:** C. Ethylene oxide gas sterilization is a chemical method that is effective for heat-sensitive materials but is not as widely used as autoclaving.