**Core Concept**
The muscles of the tongue are primarily supplied by the hypoglossal nerve (cranial nerve XII), which is responsible for controlling the movements of the tongue. This nerve is crucial for functions such as speaking, swallowing, and manipulating food in the mouth.

**Why the Correct Answer is Right**
The hypoglossal nerve innervates all the extrinsic and intrinsic muscles of the tongue, except for the palatoglossus muscle, which is supplied by the vagus nerve (cranial nerve X). The hypoglossal nerve's motor fibers originate from the hypoglossal nucleus in the medulla oblongata and travel through the hypoglossal canal to reach the tongue. The nerve's motor functions include tongue protrusion, retraction, and lateral movements, which are essential for various oral and pharyngeal functions.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because the glossopharyngeal nerve (cranial nerve IX) primarily supplies sensory and motor functions to the pharynx, including the stylopharyngeus muscle, but not the muscles of the tongue.
**Option B:** This option is incorrect because the vagus nerve (cranial nerve X) supplies the palatoglossus muscle, but not the other muscles of the tongue. The vagus nerve also provides sensory innervation to the pharynx and larynx.
**Option C:** This option is incorrect because the facial nerve (cranial nerve VII) primarily supplies the muscles of facial expression, including the platysma muscle, but not the muscles of the tongue.

**Clinical Pearl / High-Yield Fact**
The hypoglossal nerve is vulnerable to damage during surgical procedures in the neck, such as thyroid surgery, which can lead to tongue weakness or paralysis. This is a classic exam trap, as the hypoglossal nerve is often overlooked during surgical procedures.

**Correct Answer: A. Hypoglossal nerve**