**Core Concept**
Gamma radiation is a widely used method for sterilizing medical equipment, including disposable syringes, due to its efficacy in eliminating bacteria, viruses, and other microorganisms without causing damage to the equipment. This process is often employed in the medical industry for its ability to sterilize items that are sensitive to heat and moisture.

**Why the Correct Answer is Right**
Gamma radiation works by breaking the DNA of microorganisms, rendering them unable to reproduce and thus eliminating the risk of infection. This process is particularly effective for sterilizing disposable syringes, which are often made of materials that cannot withstand high temperatures or moisture. The use of gamma radiation for sterilization also allows for a high degree of sterility to be achieved, making it an ideal method for medical equipment.

**Why Each Wrong Option is Incorrect**
**Option A:** Hot air ovens are typically used for sterilizing equipment that can withstand high temperatures, such as glassware and metal instruments. Disposable syringes, however, are often made of materials that would be damaged by the high temperatures used in hot air ovens.

**Option B:** Ultraviolet (U.V.) rays can be used to disinfect surfaces and equipment, but they are not effective for sterilizing disposable syringes. U.V. rays work by damaging the DNA of microorganisms, but they are not intense enough to achieve complete sterilization.

**Option D:** Boiling water is a common method for sterilizing equipment, but it is not suitable for disposable syringes. The high temperatures and moisture associated with boiling water can damage the materials used to make disposable syringes, making them unusable.

**Clinical Pearl / High-Yield Fact**
It's essential to note that gamma radiation sterilization is a widely accepted method for sterilizing medical equipment, including disposable syringes. This method is particularly useful for equipment that is sensitive to heat and moisture, making it a critical tool in the medical industry.

**✓ Correct Answer: C. Gamma rays**