**Core Concept**
The treatment of ureteric calculi with laser involves the use of a specific type of high-energy beam to break down or disintegrate the stone. This procedure is known as laser lithotripsy, which is a minimally invasive technique used to treat kidney stones.

**Why the Correct Answer is Right**
The correct laser used in the treatment of ureteric calculi is the Holmium:Yttrium-Aluminum-Garnet (Ho:YAG) laser. This laser emits a 2,100-nm wavelength beam that is highly absorbed by water, which makes it ideal for breaking down kidney stones without causing significant damage to surrounding tissues. The Ho:YAG laser works by generating shockwaves that disintegrate the stone into smaller fragments that can then be easily passed out of the body.

**Why Each Wrong Option is Incorrect**
* **Option A:** Nd:YAG laser - Although the Nd:YAG laser is also a type of laser, it emits a 1,064-nm wavelength beam that is less effective for breaking down kidney stones due to its lower absorption by water.
* **Option B:** Argon laser - The Argon laser emits a 488-nm wavelength beam that is not suitable for breaking down kidney stones, as it is not absorbed by water and can cause significant damage to surrounding tissues.
* **Option C:** Excimer laser - The Excimer laser emits a 193-nm wavelength beam that is used for corneal resurfacing and other ophthalmic procedures, but it is not used for laser lithotripsy.

**Clinical Pearl / High-Yield Fact**
The Ho:YAG laser is the gold standard for laser lithotripsy due to its high success rate and minimal complications.

**Correct Answer: C. Ho:YAG laser**