2 (3) 3.a. A ta field. ble has six fields, express the projection mapping to remove both the second and fifth 3.b. What is the best choice for a primary key Product Name, Quantity, Price. field of the following relation: BarCodeNumber, 3.c. Identify the clauses of this SQL statement which correspond to the selection, projection and join operations of a n-ary relation? SELECT FlightNumber, Origin, Destination, Seat, PassengerName FROM Flights, PassengerReservations WHERE Departureime = 0930