- A$135^{\circ}$
- B$120^{\circ}$
- C$60^{\circ}$
- ✓$45^{\circ}$
Now, supplementary of the required angle $=180^{\circ}- x$
Then,
$x+\frac{1}{3}\left(180^{\circ}-x\right)=90^{\circ}$
$\Rightarrow 3 x+180^{\circ}-x=270^{\circ}$
$\Rightarrow 2 x=90^{\circ}$
$\Rightarrow x=45^{\circ}$
Hence, the correct answer is option $(d).$


































