Two large vertical and parallel metal plates having a separation of 1 cm are connected to a DC voltage source of potential difference X . A protonis released at rest midway between the two plates. It is found to move at $$45^\circ$$ to the vertical JUSTafter release. Then X is nearly

A

$$1 \times 10^{-5}$$ V

B

$$1 \times 10^{-7}$$ V

C

$$1 \times 10^{-9}$$ V

D

$$1 \times 10^{-10}$$ V