Assume that RMO will begin by asking a random sample of customers who order by telephone about purchases made from competitors. RMO will give customers a 15 percent discount on their current order in exchange for answering a few questions. To store and use this information, RMO will add two new classes and three new associations to the class diagram. The new classes are Competitor and ProductCategory. A competitor has a one-to-many association with ProductCategory, and the existing Customer class also has a one-to-many association with ProductCategory. A competitor has a single attribute called Name. ProductCategory has four attributes: Description, dollar amount purchased, MonthPurchased, and year purchased. Revise the relational database schema shown in Figure 9-10 to include the new classes and associations. All tables must be in 3NF.