**Core Concept**
Angle closure glaucoma occurs due to the closure of the anterior chamber angle, leading to increased intraocular pressure (IOP). Laser iridotomy is a surgical procedure that creates a hole in the iris to alleviate this obstruction, thereby reducing IOP. The primary goal of this procedure is to restore the normal outflow of aqueous humor from the eye.

**Why the Correct Answer is Right**
The laser used for iridotomy is typically a neodymium-doped yttrium aluminum garnet (Nd:YAG) laser. This high-energy laser creates a precise hole in the iris, allowing for the free flow of aqueous humor and reducing IOP. The Nd:YAG laser emits a beam of infrared light that is selectively absorbed by water, causing it to vibrate and create a plasma, which ultimately leads to the disruption of the iris tissue.

**Why Each Wrong Option is Incorrect**
**Option A:** Argon laser is incorrect because it is primarily used for photocoagulation, such as in diabetic retinopathy, and is not suitable for creating a precise hole in the iris.
**Option B:** Excimer laser is incorrect because it is used for corneal and refractive surgeries, such as LASIK, and is not used for iridotomy.
**Option C:** Holmium laser is incorrect because it is used for urological and orthopedic procedures, such as lithotripsy and orthopedic surgery, and is not typically used for ophthalmic procedures.

**Clinical Pearl / High-Yield Fact**
The Nd:YAG laser is a valuable tool in ophthalmology, particularly for treating angle closure glaucoma and posterior capsular opacification after cataract surgery. Its ability to create a precise hole in the iris or posterior capsule makes it an essential component of modern ophthalmic surgery.

**Correct Answer:** C. Holmium laser.