**Core Concept**
Pleomorphic adenoma, also known as a benign mixed tumor, is a type of salivary gland tumor that exhibits a wide range of cellular and histological diversity. It is the most common type of salivary gland tumor and typically arises from the epithelial elements of the gland.

**Why the Correct Answer is Right**
Pleomorphic adenomas are most commonly found in the parotid gland, which is the largest of the salivary glands and located in front of the ear. This is because the parotid gland has a larger number of epithelial cells, which are the cells of origin for pleomorphic adenomas. The tumor often arises from the deep lobe of the parotid gland, which is a part of the gland located deeper in the neck.

**Why Each Wrong Option is Incorrect**
* **Option A:** While the submandibular gland is a common site for other types of salivary gland tumors, it is not the most common site for pleomorphic adenomas.
* **Option B:** The minor salivary glands are a common site for other types of salivary gland tumors, but pleomorphic adenomas are rare in these glands.
* **Option C:** The sublingual gland is a small gland located under the tongue, and it is not a common site for pleomorphic adenomas.

**Clinical Pearl / High-Yield Fact**
Pleomorphic adenomas are typically slow-growing and benign, but they can cause symptoms due to their size and location. They are often found incidentally during imaging studies or physical examination, and surgical excision is usually the treatment of choice.

**Correct Answer:** A.