What is the completely factored form of d4 - 8d2 + 16?. A) (d2 + 4) (d2 - 4). B) (d2 - 4) (d2 - 4). C) (d2 + 4) (d + 2) (d - 2). D) (d + 2) (d - 2) (d + 2) (d - 2)

For a quadratic equation, the negative of the numerical coefficient of the second term is the sum of the roots and the constant is their product. Let a and b be the roots such that,

a + b = 8

ab = 16

The values of a and b are 4 and 4. Such that the factors are,

(d² - 4) (d² - 4)

Both the factors are difference of two squares. The final answer for this item is,

(d + 2) (d - 2) (d + 2) (d - 2)

This is letter D.