Step 1: Analysis
The circuit shows two inductors $L$ in parallel and two capacitors $C$ in series.
- $L_{\text{eq}} = L/2$
- $C_{\text{eq}} = C/2$
Step 2: Formula
Resonant frequency $f = \frac{1}{2\pi\sqrt{L_{\text{eq}} C_{\text{eq}}}}$.
Step 3: Calculation
$f = \frac{1}{2\pi\sqrt{(L/2)(C/2)}} = \frac{1}{2\pi\sqrt{LC/4}}$
$f = \frac{1}{2\pi (1/2) \sqrt{LC}} = \frac{1}{\pi\sqrt{LC}}$.
Step 4: Conclusion
Hence, the frequency is $\frac{1}{\pi\sqrt{LC}}$.
Final Answer: (C)