The correct option is
C Saliva is secreted by six pairs of glands
The salivary glands in mammals are exocrine glands that produce saliva through a system of ducts. Humans have three paired major salivary glands (parotid, submandibular, and sublingual), a pair of seromucous tubarial glands as well as hundreds of minor salivary glands.
Hence, the correct answer is (C)