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)
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)