if (x-1)^4=16,then the sum of non real complex values of x=?

(x - 1)^4 = 16
(x - 1)^4 - 2^4 = 0
[(x - 1)^2 + 2^2][(x - 1)^2 - 2^2] = 0
[(x - 1) + 2i][(x - 1) - 2i][(x - 1) + 2][(x - 1) - 2] = 0

x = 1 - 2i, 1 + 2i, -1 or 3

Therefore, the sum of non real complex values of x
= 1 - 2i + 1 + 2i
= 2 (option a)

(x-1)^4=16
x-1 = 4^V16
x-1 = 2
x = 2+1
x=3