Figure 3-13 shows the development of entity clusters for the Pine Valley Furniture E-R diagram. In Figure 3-13b, explain the following:

a. Why is the minimum cardinality next to the DOES BUSINESS IN associative entity coming from CUSTOMER zero?

b. What would be the attributes of ITEM (refer to Figure 2-22)?

c. What would be the attributes of MATERIAL (refer to Figure 2-22)?

CUSTOMER CUSTOMER SELUNG UNIT SALESPERSON Customer Type National? Regular? Submits Customer Type Serves DOES BUSINESS IN NATIONAL CUSTOMER REGULAR CUSTOMER SALES TERRITORY Account Manager PRODUCT INE ORDER ITEM SALE Includes VENDOR PRODUCT ORDER LINE SUPPLIER USES PRODUCED IN Contract Number MATERIAL SUPPLIES RAW MATERIAL WORK CENTER 23 EMPLOYEE WORKS IN SKILL HAS SKILL Employee Type d) Employee Type "M" "U" MANAGEMENT EMPLOYEE UNION EMPLOYEE MANUFACTURING Supervises