1. What is sputum?
a. A slightly alkaline secretion of water, mucin, protein, salts, and often a starch-splitting enzyme that is secreted into the mouth by salivary glands
b. A viscid, slippery secretion that is usually rich in mucins and is produced by mucous membranes
c. The liquid that fills the space between most of the cells of the body
d. The matter discharged from the air passages in diseases of the lungs, bronchi, or upper respiratory tract