The correct answer is Fibroma, as it is the most frequently diagnosed benign tumor of the oral cavity. It commonly arises due to chronic irritation or trauma, leading to a reactive hyperplasia of fibrous connective tissue. Unlike true neoplasms, fibromas represent a localized fibrous tissue overgrowth. They are typically firm, painless, and slow-growing. Other options like papilloma, lipoma, and neurofibroma are less common in the oral cavity.

Reference:
Shafer's Textbook of Oral Pathology, 7th Edition, Volume 1, Chapter 3, Page 58