Answer:
Mr. Barnett's store is called the Barnett Mercantile because:
C. Mercantile describes a place for trading or selling.
Explanation:
As an adjective, the word mercantile refers to anything related to commerce or trading. As a noun, even though it isn't commonly used nowadays, mercantile means store, that is, a place for trading or selling. That is why Mr. Barnett's story is called Barnett's Mercantile. The word has its origins in Latin, from mercant- and mercans (merchant), related to the participle mercari (to trade).