5. If the graphs of the equations $3 x+b y+c=0$ and $c x-2 y+12=0$ coincide, let $n$ be the number of pairs $(b, c)$ that satisfy the above conditions, then $n$ equals ( ).
(A) $0 \quad$ (B) 1
(C) 2
(D) finite but more than 2
5. (C).

Given the equations can be transformed into $y=\frac{3}{b} x-\frac{c}{b}, y=\frac{c}{2} x+6$. If the two lines coincide, then we should have $\left\{\begin{array}{c}\frac{3}{b}=\frac{c}{2}, \\ \frac{c}{b}=6 .\end{array}\right.$ Solving this, we get $(b, c)$ as $(-1,6),(1,-6)$.