**Core Concept**
Effective sterilization is crucial in medical and laboratory settings to prevent the spread of infection. Various agents are used for sterilization, each with its unique mechanism of action and spectrum of activity.

**Why the Correct Answer is Right**
The correct answer is Ethylene Oxide (ETO), which is a potent gas used for sterilizing heat-sensitive equipment and materials. ETO works by alkylating DNA, RNA, and proteins, ultimately leading to the death of microorganisms. It is particularly effective against bacterial spores, which are highly resistant to other sterilizing agents.

**Why Each Wrong Option is Incorrect**
**Option A:** Glutaraldehyde is a disinfectant and sterilant used for medical equipment, but it is not the primary agent used for sterilization of heat-sensitive materials.
**Option B:** Ethanol and isopropanol are used as disinfectants and antiseptics, but they are not effective against bacterial spores and are not used for sterilization.
**Option C:** Hydrogen peroxide is used as a disinfectant and sterilant, but it is not the preferred agent for sterilizing heat-sensitive materials.

**Clinical Pearl / High-Yield Fact**
Ethylene Oxide is a potent gas that can be used to sterilize a wide range of materials, including plastics, metals, and glassware.

**Correct Answer:** C. Ethylene Oxide