**Core Concept**
Gamma radiations are a type of ionizing radiation used for sterilization, which involves the elimination of microorganisms from medical devices and equipment. This process is based on the principle of ionizing radiation-induced DNA damage, leading to the death of microorganisms.

**Why the Correct Answer is Right**
The correct answer is based on the fact that gamma radiations have sufficient energy to cause double-strand breaks in the DNA of microorganisms, leading to cell death. Gamma radiations interact with the DNA molecule, causing breaks in the phosphodiester backbone and leading to the activation of repair mechanisms, which ultimately results in cell death. This process is effective against all types of microorganisms, including bacteria, viruses, and spores.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because gamma radiations are not typically used for surface disinfection. Surface disinfection is usually achieved through the use of chemical disinfectants or ultraviolet (UV) light.

**Option B:** This option is incorrect because electron beam radiation is a type of ionizing radiation used for sterilization, but it is not as effective as gamma radiations for achieving high levels of sterility.

**Option C:** This option is incorrect because UV light is a type of non-ionizing radiation used for surface disinfection and some types of water treatment, but it is not effective for sterilizing medical devices and equipment.

**Clinical Pearl / High-Yield Fact**
It's essential to note that gamma radiation sterilization can be used for a wide range of medical devices and equipment, including implants, surgical instruments, and disposable medical supplies.

**Correct Answer: D. Gamma radiations are used for sterilizing medical devices and equipment, including implants, surgical instruments, and disposable medical supplies.**