Approximate the real number solution(s) to the polynomial function f(x) = x3 − 4x2 + x + 6.
A. x = −3, x = −1, x = 2
B. x = 3, x = 1, x = −2
C. x = 3, x = −1, x = 2
D. x = −3, x = 1, x = −2