**Core Concept**
The deep lobe of the parotid gland is located deep to the facial nerve and is in close proximity to the parapharyngeal space. The parapharyngeal space is a fascial space that extends from the base of the skull to the level of the hyoid bone and is bounded by the prevertebral fascia, the carotid sheath, and the pharyngeal constrictor muscles.

**Why the Correct Answer is Right**
When the deep lobe of the parotid gland becomes swollen, it can extend into the parapharyngeal space, causing a mass effect. This is because the fascial planes between the deep lobe of the parotid gland and the parapharyngeal space are relatively thin and can be easily traversed by the swelling. As a result, swelling of the deep lobe of the parotid gland can present as a swelling in the parapharyngeal space, which can be a diagnostic challenge. The parapharyngeal space is also a common site for other types of pathology, such as abscesses and tumors, which can mimic the presentation of a swollen deep lobe of the parotid gland.

**Why Each Wrong Option is Incorrect**
**Option B:** Swelling of the deep lobe of the parotid gland would not typically present as a swelling in the cheek, as the facial nerve and the superficial lobe of the parotid gland are located in the superficial plane and would be more likely to be involved.

**Option C:** Swelling of the deep lobe of the parotid gland would not typically present as a swelling in the temporal region, as the deep lobe is located more medially and is not directly related to the temporal region.

**Option D:** Swelling of the deep lobe of the parotid gland would not typically present as a swelling below the ear, as the facial nerve and the superficial lobe of the parotid gland are located in the superficial plane and would be more likely to be involved.

**Clinical Pearl / High-Yield Fact**
A key clinical correlation to remember is that swelling of the deep lobe of the parotid gland can be a "silent" mass, as it may not be immediately apparent on physical examination. A thorough head and neck examination, including palpation of the parapharyngeal space, is essential to diagnose this condition.

**✓ Correct Answer: A. Parapharyngeal space**