which of the following is the correct representation of the polynomial
f(x) = x4 - 2x3 + 2x - 1 as a product of linear factors?

a. f(x) = (x+1)(x - 1)(x - 1)(x+1)
b. f(x) = (x - 1)(x - 1)(x - 1)(x + 1)
c. f(x) = (x-1)(x-1)(x - 1)(x - 1)
d. f(x) = (x + 1)(x + 1)(x+1)(x + 1)