Answer: MC stands for Methyl Cellulose, which is derived from refined cotton treated with alkali. It is then etherified using methyl chloride as the etherifying agent, resulting in cellulose ether through a series of reactions. The degree of substitution is generally between 1.6 and 2.0, and different degrees of substitution result in different solubilities. It belongs to the nonionic type of cellulose ether.