Which is not a polynomial?

question 2 options:

4/x4+3/x3− 2/x2−1

x^5 − 5x^4 + 4x^3 −3x^2

3x^2 + 5x^4 + 2x − 12

x^3− 7x^2 + 9x −20

Let u = {q, r, s, t, u, v, w, x, y, z} a = {q, s, u, w, y} b = {q, s, y, z} c = {v, w, x, y, z}. list the elements in the set. a ∩ (b ∪ c)a) {q, s, w, y}b) {q, y, z}c) {q, s, u, w, y, z}d) {q, r, w, y, z}