**Core Concept**
During surgical excision of a ranula, the surgeon must be aware of the anatomical structures at risk of damage. A ranula is a type of mucocele that occurs on the floor of the mouth, resulting from obstruction of the sublingual gland or duct. The surgical approach requires careful dissection to avoid damaging nearby vital structures.

**Why the Correct Answer is Right**
The submandibular duct is the most commonly damaged structure during surgery on a ranula due to its close proximity to the ranula itself. The duct runs superficially in the floor of the mouth, making it vulnerable to injury during surgical excision of the ranula. Damage to the submandibular duct can lead to salivary fistula, which can complicate the postoperative course. The surgeon must therefore exercise caution when dissecting the floor of the mouth to avoid damaging this duct.

**Why Each Wrong Option is Incorrect**
* **Option A:** The lingual artery is a vital structure that supplies the tongue and floor of the mouth. While it is located in the floor of the mouth, it is not the most commonly damaged structure during surgery on a ranula.
* **Option B:** The lingual nerve is a branch of the mandibular division of the trigeminal nerve that provides sensation to the tongue. While it is located in the floor of the mouth, it is not as commonly damaged as the submandibular duct during surgery on a ranula.
* **Option D:** The sublingual duct is a minor salivary gland duct that opens into the floor of the mouth. While it is located in the floor of the mouth, it is not as commonly damaged as the submandibular duct during surgery on a ranula.

**Clinical Pearl / High-Yield Fact**
During surgery on a ranula, the surgeon should identify the submandibular duct and carefully dissect the floor of the mouth to avoid damaging this duct. The use of a surgical loupe or microscope can help to identify the duct and surrounding structures, reducing the risk of damage.

**✓ Correct Answer: C. Submandibular duct**