**Core Concept**
The ethmoidal sinus is a paired paranasal sinus located between the nasal cavity and the eye, and it is innervated by the trigeminal nerve (cranial nerve V). The trigeminal nerve has three main divisions: ophthalmic (V1), maxillary (V2), and mandibular (V3). The ethmoidal sinus is specifically innervated by the anterior and posterior ethmoidal nerves, which are branches of the nasociliary nerve (a branch of the ophthalmic division, V1).

**Why the Correct Answer is Right**
The pain sensations from the ethmoidal sinus are carried by the anterior and posterior ethmoidal nerves, which are branches of the nasociliary nerve. The nasociliary nerve is a branch of the ophthalmic division (V1) of the trigeminal nerve, which is responsible for the sensory innervation of the face, including the nasal cavity and the paranasal sinuses. The ethmoidal sinus is a highly innervated structure, and its pain sensations are primarily carried by the anterior and posterior ethmoidal nerves.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because the maxillary nerve (V2) primarily innervates the maxillary sinus, the palate, and the lower eyelid, and not the ethmoidal sinus.
**Option B:** This option is incorrect because the mandibular nerve (V3) primarily innervates the lower face, including the lower lip, the lower teeth, and the skin of the lower face, and not the ethmoidal sinus.
**Option D:** This option is incorrect because the glossopharyngeal nerve (cranial nerve IX) primarily innervates the pharynx, the tonsils, and the stylopharyngeus muscle, and not the ethmoidal sinus.

**Clinical Pearl / High-Yield Fact**
The trigeminal nerve is responsible for the sensory innervation of the face, including the nasal cavity and the paranasal sinuses. The anterior and posterior ethmoidal nerves are branches of the nasociliary nerve, which is a branch of the ophthalmic division (V1) of the trigeminal nerve.

**Correct Answer: C. The ophthalmic division (V1) of the trigeminal nerve.**