**Core Concept**
The parotid gland is one of the major salivary glands, responsible for the production of serous saliva. The parotid duct, also known as Stensen's duct, is a structure that carries saliva from the parotid gland to the oral cavity.

**Why the Correct Answer is Right**
The parotid duct, also known as Stensen's duct, is a significant anatomical landmark that opens into the oral cavity, specifically into the cheek, near the second upper molar tooth. The duct is approximately 5 cm long and is located behind the masseter muscle. The saliva secreted by the parotid gland through Stensen's duct plays a crucial role in the digestion of carbohydrates and the maintenance of oral hygiene.

**Why Each Wrong Option is Incorrect**
**Option A:**
This option is incorrect as it does not accurately describe the parotid duct. The submandibular gland's duct, also known as Wharton's duct, opens into the oral cavity near the lingual frenulum.

**Option B:**
This option is incorrect as it refers to the duct of the sublingual gland, which opens into the floor of the mouth.

**Option C:**
This option is incorrect as it does not accurately describe the parotid duct. The accessory parotid gland's ducts may open into the oral cavity, but they are not the primary parotid duct.

**Clinical Pearl / High-Yield Fact**
It's essential to recognize the location of the parotid duct, as inflammation or infection of the duct can lead to pain and swelling in the region, known as parotitis.

**Correct Answer: C. Stensen's duct.