**Core Concept**
The parasympathetic nervous system (PNS) is a branch of the autonomic nervous system that promotes rest, digestion, and other 'housekeeping' functions. The PNS supplies various glands, including the lacrimal gland, which produces tears. The lacrimal gland receives its parasympathetic innervation from the facial nerve (cranial nerve VII).

**Why the Correct Answer is Right**
The greater petrosal nerve is a branch of the facial nerve that carries preganglionic parasympathetic fibers to the pterygopalatine ganglion. From the pterygopalatine ganglion, postganglionic fibers are transmitted to the lacrimal gland through the nerve of the pterygoid canal. This parasympathetic innervation stimulates the lacrimal gland to secrete tears. The lacrimal gland is responsible for tear production, maintaining eye health and clarity of vision. The parasympathetic stimulation of the lacrimal gland is mediated by the release of acetylcholine, a neurotransmitter released by the preganglionic fibers of the parasympathetic nervous system.

**Why Each Wrong Option is Incorrect**
**Option A:** The lesser petrosal nerve carries preganglionic parasympathetic fibers from the glossopharyngeal nerve (cranial nerve IX) to the otic ganglion, which supplies the parotid gland, not the lacrimal gland.

**Option B:** The chorda tympani is a branch of the facial nerve that carries taste fibers from the anterior two-thirds of the tongue and preganglionic parasympathetic fibers to the submandibular ganglion, which supplies the submandibular and sublingual glands. It does not supply the lacrimal gland.

**Option D:** The lingual nerve is a branch of the mandibular division of the trigeminal nerve (cranial nerve V) that provides sensory innervation to the tongue, including taste and general sensation. It does not carry parasympathetic fibers to the lacrimal gland.

**Clinical Pearl / High-Yield Fact**
The greater petrosal nerve is often remembered as the nerve that supplies the lacrimal gland, along with the pterygopalatine ganglion. This is a key point to recall for exams, as the parasympathetic innervation of the lacrimal gland is essential for tear production and maintaining eye health.

**✓ Correct Answer: C. Greater petrosal nerve**