Question

Add the proper constant to each binomial so that the resulting trinomial is a perfect square trinomial. Then factor the trinomial.
x2 + 18x + _______

A) x2 + 18x + 324 = (x + 18)2
B) x2 + 18x + 18 = (x + 324)2
C) x2 + 18x + 9 = (x + 81)2
D) x2 + 18x + 81 = (x + 9)2