If –1 is a root of f(x), which of the following must be true?

a. A factor of f(x) is (x – 1).

b. A factor of f(x) is (x + 1).

c. Both (x – 1) and (x + 1) are factors of f(x).

d. Neither (x – 1) nor (x + 1) is a factor of f(x).

If –1 is a root of f(x), which of the following must be true?

a. A factor of f(x) is (x – 1).

b. A factor of f(x) is (x + 1).

c. Both (x – 1) and (x + 1) are factors of f(x).

d. Neither (x – 1) nor (x + 1) is a factor of f(x).