Explanation

(d)
Equation of a line passing through the intersection of lines $ax + 2by + 3b = 0$ and $bx - 2ay - 3a = 0$ is
$(ax + 2by + 3b) + \lambda(bx - 2ay - 3a) = 0$ …(i)
Now, this line is parallel to $x$-axis, so coefficient of $x$ should be zero.
$ie,\ a + \lambda b = 0$
$\Rightarrow \ \lambda = - \frac{a}{b}$
On putting this value in Eq. (i), we get
$b(ax + 2by + 3b) - a(bx - 2ay - 3a) = 0$
$\Rightarrow 2\left( b^{2} + a^{2} \right)y + 3\left( b^{2} + a^{2} \right) = 0$
$\Rightarrow y = - \frac{3}{2}$
The negative sign shows that the line is below $x$-axis, at a distance $\frac{3}{2}$ from it.