**Core Concept**
X-rays are a form of ionizing radiation that can cause damage to living tissues by altering the chemical bonds within DNA. This damage can lead to mutations, cell death, or cancer. The primary mechanism of radiation damage is through the ionization of water molecules, which results in the formation of free radicals.

**Why the Correct Answer is Right**
Ionization is the process by which X-rays interact with matter, resulting in the ejection of tightly bound electrons from atoms. This process occurs when the energy of the X-ray photon is sufficient to overcome the binding energy of the electron. The resulting free radicals can cause oxidative stress, DNA damage, and ultimately, cell death. The ionization of water molecules is the primary mechanism by which X-rays cause radiation damage.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because ionization is the primary mechanism of radiation damage caused by X-rays.
* **Option B:** This option is incorrect because X-rays do not primarily cause radiation damage through their property of being a form of electromagnetic radiation.
* **Option D:** This option is incorrect because X-rays do not primarily cause radiation damage through their property of having a high frequency.

**Clinical Pearl / High-Yield Fact**
It's essential to note that the risk of radiation-induced damage increases with the dose and duration of exposure. As a medical professional, it's crucial to minimize radiation exposure to patients and staff whenever possible.

**Correct Answer:** C. Ionization.