5. Given that $\mathrm { x } , \mathrm { y }$ satisfy the constraints $\left\{ \begin{array} { c } x - y \geq 0 \\ x + y - 4 \leq 0 \\ y \geq 1 \end{array} \right.$, then the maximum value of $\mathrm { z } = - 2 \mathrm { x } + \mathrm { y }$ is\\
(A) $- 1$\\
(B) $- 2$\\
(C) $- 5$\\
(D) $1$