**Core Concept**
The question is testing the knowledge of radiation therapy and its applications in treating deep-seated tumors. Radiation therapy uses ionizing radiation to destroy cancer cells, and the choice of radiation beam depends on the tumor's location, size, and depth.

**Why the Correct Answer is Right**
The correct answer is likely Gamma Rays, which are high-energy electromagnetic radiation used to treat deep-seated tumors. Gamma rays have a short range in tissue and can deliver a high dose of radiation to the tumor site, reducing damage to surrounding healthy tissue. This is particularly useful for treating tumors that are located deep within the body, such as those in the brain, spine, or pelvis. Gamma rays interact with the tumor cells through the Compton effect, causing ionization and DNA damage that leads to cell death.

**Why Each Wrong Option is Incorrect**
**Option A:** Alpha Rays are high-energy particles that are not suitable for treating deep-seated tumors due to their short range in tissue and high ionization potential, which makes them more suitable for surface treatments.
**Option B:** Beta Rays are also high-energy particles, but they have a longer range in tissue than alpha rays and are not as effective for treating deep-seated tumors.
**Option C:** X-Rays are a type of electromagnetic radiation, but they have a lower energy than gamma rays and are not as effective for treating deep-seated tumors.

**Clinical Pearl / High-Yield Fact**
When treating deep-seated tumors with radiation therapy, it's essential to choose the right radiation beam to minimize damage to surrounding healthy tissue and maximize the dose delivered to the tumor. This requires careful planning and precise targeting of the radiation beam.

**Correct Answer:** C. X-Rays are not the best choice for treating deep-seated tumors, but another option is X-rays.