**Core Concept**
Pleomorphic adenoma, also known as benign mixed tumor, is a type of salivary gland tumor that exhibits a wide range of histological features, including epithelial and mesenchymal components. This tumor is the most common type of salivary gland neoplasm, primarily affecting the parotid gland.

**Why the Correct Answer is Right**
Pleomorphic adenomas are characterized by their biphasic composition, comprising both epithelial and stromal elements. The epithelial component can take the form of various types of salivary gland cells, while the stromal component consists of myxoid, chondroid, or osseous elements. The combination of these elements gives rise to the pleomorphic nature of the tumor.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because pleomorphic adenomas are typically benign, not malignant. They have a low risk of malignant transformation, which is a key feature distinguishing them from other types of salivary gland tumors.
**Option B:** This option is incorrect because pleomorphic adenomas can occur in any salivary gland, including the parotid, submandibular, and minor salivary glands, not just the parotid gland.
**Option C:** This option is incorrect because the treatment of choice for pleomorphic adenoma is surgical excision, not radiation therapy. Radiation is typically reserved for more aggressive or malignant tumors.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that pleomorphic adenomas are the most common type of salivary gland tumor and can occur in any salivary gland. They are typically benign and can be successfully treated with surgical excision.

**Correct Answer:** A.