**Core Concept**
Iridotomy is a procedure used to create a hole in the iris, allowing fluid to drain and alleviate pressure in the eye. This is often necessary for conditions like glaucoma. The laser used in this procedure plays a crucial role in its success.

**Why the Correct Answer is Right**
The correct laser used in iridotomy is the Argon Laser. This is because Argon Lasers produce a high-energy beam of light that can precisely create small holes in the iris without causing significant damage to surrounding tissue. The Argon Laser works by emitting a wavelength of 488-514 nanometers, which is selectively absorbed by the pigment in the iris, allowing for precise cutting.

**Why Each Wrong Option is Incorrect**
**Option A:** The Neodymium (Nd) YAG Laser is not typically used for iridotomy as it has a longer wavelength and is more suited for procedures like posterior capsulotomy. It's not ideal for precise cutting in the iris.
**Option B:** The Diode Laser is not the primary choice for iridotomy due to its lower precision and potential for collateral damage. While it can be used for various ophthalmic procedures, it's not the best fit for this specific application.
**Option C:** The Excimer Laser is not used for iridotomy as it's primarily used for refractive surgery, such as LASIK, to correct vision by reshaping the cornea.

**Clinical Pearl / High-Yield Fact**
When considering laser treatments for ophthalmic conditions, it's essential to remember that the choice of laser depends on the specific procedure and the desired outcome. Different lasers have unique properties that make them more or less suitable for various applications.

**Correct Answer: B. Diode Laser.**