If he area of a sector of a circle is

We have given that area of the sector is $\frac{7}{20}$ of the area of the circle.

Therefore, area of the sector $=\frac{7}{20} \times$ area of the circle

$\therefore \frac{\theta}{360} \times \pi r^{2}=\frac{7}{20} \times \pi r^{2}$

Now we will simplify the equation as below,

$\frac{\theta}{360}=\frac{7}{20}$

Now we will multiply both sides of the equation by 360,

$\therefore \theta=\frac{7}{20} \times 360$

$\therefore \theta=126$

Therefore, sector angle is $126^{\circ}$.

Hence, the correct answer is option (d).