Two parallel plate capacitors of capacitance C and 2C are connected in parallel and charged to a potential difference V. The battery is then disconnected, and the region between the plates of C is filled completely with a material of dielectric constant K. The common potential difference across the combination becomes

• A. \[\frac{2V}{K+2}\]
• B. \[\frac{V}{K+2}\]
• C. \[\frac{3V}{K+3}\]
• D. \[\frac{3V}{K+2}\]