Two identical capacitors are joined in parallel and charged to a potential V. They are then disconnected from the battery and connected to each other in series. The positive plate of one being connected to the negative of the other and two outer plates left unconnected. Which of the following statements is correct ?

• A

  charge on the plates connected to each other is reduced to zero

• B

  charge on the (outer) free plates is doubled

• C

  potential difference between the [outer) free plates is doubled

• D

  the energy stored in the system is doubled.