Use the Factor Theorem. A term of the form x - a is a factor of P(x) only when P(a) = 0. So do not choose a factor by appearance; test the value inside the bracket. For this polynomial, the correct listed factors are x - (-3), x - (1). In other words, x - (-3) because P(-3) = 0, x - (1) because P(1) = 0. The other options are not factors because substituting their corresponding values does not make the polynomial equal to zero.