选出这道题的正确选项，并且告诉我在什么位置时合外力以及加速度最大---**Extraction Content:** **Question Stem:** 例 4. (单选) (2020 七中高二段一)如下图 A、B 为两个等量的正点电荷, 在其连线中垂线上的 P 点放一个负点电荷 q(不计重力), 由静止释放后, 下列说法中正确的是 ( ) **Diagram Description:** Type: Electrostatics diagram. Main Elements: * Two points A and B are shown on a horizontal dashed line. * A point O is located midway between A and B on the horizontal dashed line. * A point P is located above O on a vertical dashed line. * Point A is labeled with charge +Q. * Point B is labeled with charge +Q. * Point P is labeled with charge q (implied to be negative from the question stem). * The line connecting A and B is dashed. * The line passing through O and P perpendicular to the line AB is dashed and vertical. **Options:** A. 点电荷在从 P 点到 0 点运动的过程中, 加速度越来越大, 速度越来越大 B. 点电荷在从 P 点到 0 点运动的过程中, 加速度越来越小, 速度越来越大 C. 点电荷运动到 0 点时加速度为零, 速度达最大值 D. 点电荷越过 0 点后, 速度越来越小, 加速度越来越大, 直到粒子速度为零