For years, the Atlantic Tool Company maintained all operations—purchasing, marketing, etc.—in its Charlotte, North Carolina, headquarters. However, as a result of sustained growth in the company's market, Atlantic has established facilities in three other cities. Each of these has its own purchasing and marketing departments, and each oversees its respective region of the country. In other words, Atlantic has changed from a ________ structure. a. Centralized b. Functional c. Decentralized d. Matrix