An inductor of inductance $L$, a capacitor of capacitance $C$ and a resistor of resistance $R$ are connected in series to an ac source of potential difference $V$ volts. Potential difference across $L,C$ and $R$ is $40\text{V},10\text{V}$ and $40\text{V}$, respectively. The amplitude of current flowing through LCR series circuit is $10\sqrt{2}$. The impedance of the circuit is:

1. A
   $4\Omega$
2. B
   $5\Omega$
3. C
   $4\sqrt{2}\Omega$
4. D
   $5\sqrt{2}\Omega$