Features and functions of the mucous cells

Mucous is a viscous fluid that lines the entire digestive tract and respiratory tract

Explanation:

Mucous is composed of  epithelial cells, dead leukocytes,water ,mucin and inorganic salts.It is chiefly produced by mucous cells which clustered in small gland situated in the mucous membrane is lining of the digestive tract.Mucous cells are largely found in the mouth where they lubricate the food  and keeps the oral membrane moist when they are in contact with air..Mucous in nasal cavity helps to trap bacteria and dust particle during inhalation. Gastric mucous protects the stomach from highly acidic gastric juice.

The main function of a mucous fluid  is to lubrication and protective many of passages of digestive and respiratory tracts.

cancer   is   essentially   uncontrolled   mitosis   of specialized cells

the answer is d. chordata