Ans: D
I is true. Consider the slope of $L_1$.
I is true. Consider the slope of $L_1$.
$\begin{array}{rcl}
m_{L_1} & > & 0 \\
\dfrac{-3}{a} & > & 0 \\
a & < & 0
\end{array}$
Consider the slope of $L_2$.
$\begin{array}{rcl}
m_{L_2} & > & 0 \\
-c & > & 0 \\
c & < & 0
\end{array}$
According to the figure, we have
$\begin{array}{rcl}
m_{L_1} & > & m_{L_2} \\
\dfrac{-3}{a} & > & -c \\
\dfrac{3}{a} & < & c \\
3 & < & ac
\end{array}$
II is not true. According to the figure, we have
$\begin{array}{rcl}
\text{$y$-intercept of $L_1$} & > & \text{$y$-intercept of $L_2$} \\
\dfrac{b}{a} & > & d \\
b & < & ad
\end{array}$
III is true. According to the figure, we have
$\begin{array}{rcl}
\text{$x$-intercept of $L_1$} & > & \text{$x$-intercept of $L_2$} \\
\dfrac{b}{3} & > & \dfrac{d}{c} \\
bc & < & 3d
\end{array}$
