40. 已知方程組 $\left\{ \begin{array}{l} x - 2y + z = a \\ x - 9y + 5z = b \\ 2x + 3y - 2z = c \end{array} \right.$，則下列哪個選項之 $a$，$b$，$c$ 可使得該方程組有解？ (A) $a = 1, b = 2, c = 3$ (B) $a = 4, b = 5, c = 6$ (C) $a = \frac{1}{6}, b = \frac{1}{3}, c = \frac{1}{6}$ (D) $a = \frac{1}{3}, b = \frac{1}{2}, c = \frac{1}{4}$