Match each of the set on the left described in the roster form with the same set on the right described in the set-builder form: (i) {P, R, I, N, C, A, L} (ii) {0} (iii) {1, 2, 3, 6, 9, 18} (iv) {3, -3} (a) {x : x is a positive integer and is a divisor of 18} (b) {x : x is an integer and x^2 - 9 = 0} (c) {x : x is an integer and x + 1 = 1} (d) {x : x is a letter of the word PRINCIPAL}