The system of linear equations
$$x + y + kz = 1$$
$$x + ky + z = 1$$
$$kx + y + z = 1$$
has

A

a unique solution for only one value of $$k$$

B

a unique solution for infinitely many choices of $$k$$

C

no solution for any value of $$k$$

D

infinitely many solutions for any value of $$k$$