$x - n y + z = 6$
$\mathbf { x } - ( \mathbf { n } - \mathbf { 2 } ) \mathbf { y } + ( \mathbf { n } + \mathbf { 1 } ) \mathbf { z } = \mathbf { 8 }$
$( \mathrm { n } - 1 ) \mathrm { y } + \mathrm { z } = 1$
Let $\mathbf { n } \boldsymbol { = }$ number on the dies when rolled randomly then $\mathbf { P }$ (that system equation has unique solution) $= \left( \frac { \mathrm { k } } { 6 } \right)$ then sum of value of k and all possible value of n is
(A) 22
(B) 24
(C) 20
(D) 21