Suppose that X and Y are sets, X - Y = u, v, w, x, y, z, Y - X = p, q, r, s, t, and X ∩ Y = 7, 8, 9. Find Y.
1. {u, v, w, x, y, z, 7, 8, 9}
2. {p, q, r, s, t, 7, 8, 9}
3. {p, q, r, s, t}
4. {u, v, w, x, y, z}