Step 1: Area of sector $$=\frac{\theta}{360^\circ}\times\pi r^2$$
Step 2: Substitute values: $$198=\frac{\theta}{360}\times\frac{22}{7}\times 18\times 18$$
Step 3: $\dfrac{22}{7}\times 324=\dfrac{7128}{7}=1018.28$, so
$$\theta=\frac{198\times 360\times 7}{22\times 324}$$
Step 4: $$\theta=\frac{498960}{7128}=70^\circ$$
Answer: (A) $70^\circ$