**Core Concept**
The middle ear cavity, also known as the tympanic cavity, is a small, air-filled space within the temporal bone that contains the ossicles responsible for transmitting sound vibrations to the inner ear. The sensory nerve supply to the middle ear cavity is crucial for detecting any potential damage or infection that may affect the function of the ossicles or the eardrum.

**Why the Correct Answer is Right**
The correct answer is the auriculotemporal nerve, which is a branch of the mandibular division of the trigeminal nerve (cranial nerve V). The auriculotemporal nerve provides sensory innervation to the middle ear cavity, including the tympanic membrane, the ossicles, and the mucous membranes lining the cavity. This nerve also carries parasympathetic fibers from the otic ganglion, which regulate the secretory function of the parotid gland.

**Why Each Wrong Option is Incorrect**
**Option A:** The greater petrosal nerve, a branch of the facial nerve, provides preganglionic parasympathetic fibers to the otic ganglion, but it does not directly innervate the middle ear cavity.

**Option B:** The tympanic plexus is a network of nerves that supplies the tympanic membrane and the middle ear cavity, but it is not the primary sensory nerve supply.

**Option C:** The glossopharyngeal nerve (cranial nerve IX) provides sensory innervation to the pharynx and the posterior one-third of the tongue, but it does not innervate the middle ear cavity.

**Clinical Pearl / High-Yield Fact**
The auriculotemporal nerve is a key landmark for surgeons performing middle ear surgery, as it must be carefully preserved to avoid damage to the facial nerve and other nearby structures.

**Correct Answer: C. Auriculotemporal nerve.**