Books (bid: integer, btitle: string, bgenre: string) Publishers (pid: integer, pname: string, paddress: string) Catalog (bid, pid, ccost: float) The key fields are underlined, and the domain of each field is listed after the field name. Thus, bid is the key for Books, pid is the key for Publishers, and bid and pid form the key for Catalog, Relation Catalog gives the prices charged for Books by Publishers. 4. (10 Points) What does the following TRC query compute: (Ep2 (11 Epl Publisher(t1.pid = pl.pid A Bel E Catalog(cl.pid = pl.pid Publisher A302 Catalog(c2.pid=p2.pid Acl.ccost