Answer: a) goblet cells
Step-by-step explanation:
Goblet cells are unicellular exocrine glands that are found along simple cylindrical epithelial and cylindrical pseudostratified epithelia. These goblet cells synthesize and secrete mucus, and have a basal nucleus. They are mainly located in the lining of the respiratory tract (trachea) and the digestive tract. Goblet cells produce glycoproteins, that originate mucus which lubricates the small intestine. Goblet cells are found in large numbers in the large intestine, and the mucus contributes to the fecal bolus compacting and facilitates the sliding of the epithelial surface.