Let one root of the quadratic equation in x:
$$(k^2 - 15k + 27)x^2 + 9(k - 1)x + 18 = 0$$
be twice the other. Then the length of the latus rectum of the parabola $$y^2 = 6kx$$ is equal to:

A

4

B

6

C

8

D

12