A series $\text{LCR}$ circuit consisting of $R=10 \; \Omega$, $\left|X_{L}\right|=20 \; \Omega$ and $\left|X_{C}\right|=20 \; \Omega$, is connected across an $a . c$. supply of $200 \text{V rms}$ . The $\text{rms}$ voltage across the capacitor is
- $200 \; \angle-90^{\circ} \; \mathrm{V}$
- $200 \; \angle+90^{\circ} \; \mathrm{V}$
- $400 \; \angle-90^{\circ} \; \mathrm{V}$
- $400 \; \angle-90^{\circ} \; \mathrm{V}$