The circuit in the figure employs positive feedback and is intended to generate sinusoidal oscillation. If at a frequency f_0, B ( f ) = V_ f ( f ) V_0 ( f ) = 1/6 0^ then to sustain oscillation at this frequency

The circuit in the figure employs positive feedback and is intended to generate sinusoidal oscillation.
If at a frequency $${\text{f}}_0,\text{B}\left(\text{f}\right)=\frac{{\text{V}}_{\text{f}}\left(\text{f}\right)}{{\text{V}}_0\left(\text{f}\right)}=\frac{1}{6}\angle 0^{\circ }$$     then to sustain oscillation at this frequency

Answer: Option A