Which of these is NOT a pair of salivary glands?

A: The largest of the salivary glands, the parotid glands, are serious glands located just anterior to each ear. Parotid ducts enter the oral cavity adjacent to the second upper molars. B: The submandibular glands produce more serious than mucous secretions. Each gland can be felt like a soft lump along the inferior border of the mandible. The submandibular ducts open into the oral cavity on each side of the frenulum of the tongue. D: The sublingual glands, the smallest of the three paired salivary glands, produce primarily mucous secretions. They lie immediately below the mucous membrane in the floor of the oral cavity