Perform the given set operation. Let U = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10}. (Enter your answers as a comma-separated list. Enter EMPTY for the empty set.) (a) {1, 2. 4} n {8, 9} { } (b) {1. 2, 4} U {3, 9} { } (C) {1, 2, 4, 8. 9}