Write x2 + 12x + 6 = 0 in vertex form using the completing-the-square method. (2 points)

a
(x - 12)2 - 30 = 0

b
(x - 6)2 + 36 = 0

c
(x + 6)2 - 30 = 0

d
(x + 12)2 + 36 = 0