**Core Concept**
The question is testing the anatomical knowledge of the tonsillar fossa, specifically the structures located on its lateral wall. The tonsillar fossa is a region in the oral cavity that houses the palatine tonsil, a lymphoid organ.

**Why the Correct Answer is Right**
The correct answer is the palatoglossal arch, also known as the palatoglossal fold. This structure is a muscular fold that forms a groove on the lateral wall of the tonsillar fossa, separating the palatine tonsil from the tongue. The palatoglossal arch is formed by the palatoglossus muscle, which is innervated by the vagus nerve. The presence of this arch is clinically significant as it is a landmark for the location of the palatine tonsil.

**Why Each Wrong Option is Incorrect**
**Option A:** The palatopharyngeal arch, also known as the palatopharyngeal fold, is located on the lateral wall of the oropharynx, not the tonsillar fossa.
**Option B:** The glossopalatine arch is not a recognized anatomical structure.
**Option C:** The lingual tonsil is located on the posterior aspect of the tongue, not on the lateral wall of the tonsillar fossa.

**Clinical Pearl / High-Yield Fact**
When examining the oropharynx, it is essential to identify the palatoglossal arch as a landmark for the location of the palatine tonsil. The presence of this arch can help in assessing the size and position of the tonsil, which is crucial in diagnosing tonsillitis or other tonsillar abnormalities.

**Correct Answer: C. Lingual tonsil is incorrect. The correct answer is actually the Palatoglossal arch formed by the Palatoglossus muscle is not given in the options.