Two media A and B of refractive indices  ${\mu }_1=1.5$ and  ${\mu }_2=2$ are separated by x-z plane. A ray of light travels from A to B. The incident ray and the reflected ray are represented by unit vectors  $\overrightarrow{u_1}=a\widehat{i}+b\widehat{j}$ and  $\overrightarrow{u_2}=c\widehat{i}+d\widehat{j}$ . Then

Applying Snell’s Law at the interface separating two media, we get

${\mu }_1\sin i={\mu }_2\sin r$

From the figure, we get
$\left(\frac{3}{2}\right)\left(\frac{a}{\sqrt{a^2+b^{{ }^2}}}\right)=2\left(\frac{c}{\sqrt{c^2+d^2}}\right) \mathrm{...}\left(1\right)$   
Since  $a\widehat{i}+b\widehat{j}$  and  $c\widehat{i}+d\widehat{j}$  are unit vectors, so we get 
 $\sqrt{a^2+b^2}=\sqrt{c^2+d^2}=1$
Substituting in equation (1), we get
 $\frac{a}{c}=\frac{4}{3}$
Hence, the correct answer is B