**Core Concept**
Durham's pin is a type of surgical instrument used in the treatment of cataracts. It is specifically designed for the extraction of the lens nucleus from the eye. The pin is used to break up the lens nucleus into smaller pieces, making it easier to remove.

**Why the Correct Answer is Right**
Durham's pin is a crucial tool in ophthalmic surgery, particularly in the extracapsular cataract extraction (ECCE) technique. The pin is used to fragment the nucleus into smaller pieces, allowing for easier aspiration. This is achieved by inserting the pin into the nucleus and then rotating it to break it up. The fragmented nucleus is then aspirated from the eye, leaving behind the lens capsule.

**Why Each Wrong Option is Incorrect**
**Option A:** Not applicable (no information provided).
**Option B:** Incorrect, as the pin is not used for vitreous gel removal.
**Option C:** Incorrect, as the pin is not used for corneal transplantation.

**Clinical Pearl / High-Yield Fact**
When using Durham's pin, it is essential to rotate the pin slowly and carefully to avoid causing further damage to the surrounding ocular tissues. The pin should be used in conjunction with a nucleus aspiration system to ensure safe and effective removal of the lens nucleus.

**Correct Answer: C. Durham's pin is used for nucleus fragmentation in cataract surgery.**