Ans: A
Note that the slope and the $y$-intercept of the straight line $ax+by+1=0$ are $-\dfrac{a}{b}$ and $-\dfrac{1}{b}$ respectively.
Note that the slope and the $y$-intercept of the straight line $ax+by+1=0$ are $-\dfrac{a}{b}$ and $-\dfrac{1}{b}$ respectively.
According to the given figure, the $y$-intercept of the straight line is negative. Then we have
$\begin{array}{rcl}
-\dfrac{1}{b} & < & 0 \\
\dfrac{1}{b} & > & 0 \\
b & > & 0
\end{array}$
Also, according to the given figure, the slope of the straight line is negative. Then we have
$\begin{array}{rcl}
-\dfrac{a}{b} & < & 0 \\
\dfrac{a}{b} & > & 0 \\
a & > & 0
\end{array}$
