Factor as Completely as Possible $$x ^ { 2 } - 16 x + 256$$

Multiple Choice

Factor as completely as possible. If unfactorable, indicate that the polynomial is prime.
- $$x ^ { 2 } - 16 x + 256$$

A) Prime
B) $( x + 16 ) ^ { 2 }$
C) $( x + 16 ) ( x - 16 )$
D) $( x - 16 ) ^ { 2 }$