A conducting sphere with no charge is placed beside a very large nonconducting plane sheet with surface charge density <img src="https://static.zxtiku.com/wangke/imgs/topic/e84aed835667d2b508cd413ea470a6aa.jpg"/>. Under the condition of electrostatic equilibrium, the potential at point P on the surface is V0 as shown in the Figure. What are the magnitude of the field and the potential at the center O?<br/> <img src="https://static.zxtiku.com/wangke/imgs/topic/ae1ccb698722d3bc6349410ebbcf2807.jpg"/><br/> A、E=0. V=V0.<br/> B、E=0. V=0.<br/> C、<img src="https://static.zxtiku.com/wangke/imgs/topic/bb1ead6a367a3602b1378bd083b67a82.jpg"/><br/> D、<img src="https://static.zxtiku.com/wangke/imgs/topic/3f39c5c55981d898328c8adf9cf1cba4.jpg"/>