The following relational schema represents Product-Supply schema: (Note that PK is underlined and bold-faced and "*" indicates FK.) PRODUCT (P#, P_NAME, PRICE. QTY) SUPPLY (S#* P** S_PRICE) SUPPLIER (S#. City). In this schema. P# = Product Number, QTY = Quantity on hand, S# = Supplier Number. PRICE in PRODUCT is the price of selling, while S_PRICE is the supplier-price supplied by the supplier. (28) P# 53 PRODUCT P NAME PRICE QTY TABLE 550 WALL UNIT 850 25 CHAIR 250 42 78 91 SUPPLY S# P# S PRICE 1253 450 1291 150 53 400 45 36 450 45 91 475 SUPPLIER S# CITY 23 NY 45 Philly DC 70 Boston 33 12 (a) Suppose we want to insert the following row of (91, STOOL, 150, 10) to Product table. Can we insert it? Why or why not? (6) (b) Suppose we want to enforce referential integrity constraints for the database. The above relations contain an important error. What is it? Be specific. (6)