Which equation shows p(x)= x^6 - 1 factored completely over the integers? (hint : you will need to use more than one method to complete this problem.)
a. p(x)= ( x - 1 ) ( x^2 + x + 1) ( x + 1 ) ( x^2 - x + 1 )
b. p(x)= ( x^3 - 1 ) ( x^3 - 1 )
c. p(x)= ( x^2 - 1 ) ( x^4 + x^2 + 1 )
d. p(x)= ( x - 1 ) ( x + 1 ) ( x^4 + x^2 + 1 )