**Core Concept**
The question tests the understanding of the parasympathetic innervation of the salivary glands and the clinical implications of facial nerve injury. The facial nerve (cranial nerve VII) has a dual role in controlling salivation: it provides parasympathetic innervation to the submandibular and sublingual glands.

**Why the Correct Answer is Right**
The correct answer is related to the site of the lesion affecting the chorda tympani, a branch of the facial nerve that carries parasympathetic fibers to the submandibular ganglion. The submandibular ganglion then relays these fibers to the submandibular and sublingual glands, promoting salivation. A lesion at this site would disrupt this pathway, leading to decreased salivation and dryness of the mouth.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because the lesion would need to be higher up in the facial nerve, affecting the nerve's motor function or its preganglionic parasympathetic fibers, which is not directly related to salivation.
* **Option B:** This option is incorrect because the lesion would need to be in the geniculate ganglion, which is involved in taste sensation and not directly related to salivation.
* **Option C:** This option is incorrect because the lesion would need to be in the stylomastoid foramen, which is where the facial nerve exits the temporal bone, but it does not directly affect the parasympathetic innervation of the salivary glands.

**Clinical Pearl / High-Yield Fact**
A lesion in the chorda tympani can also lead to impaired taste sensation on the anterior two-thirds of the tongue, as it also carries taste fibers from the anterior tongue.

**Correct Answer:** C. The lesion in the chorda tympani would lead to dryness of the mouth due to impaired parasympathetic innervation of the submandibular and sublingual glands.