Four point +ve charges of same magnitude (Q) are placed at four corners of a rigid square frame as shown in figure. The plane of the frame is perpendicular to \[\]axis. If a ?ve point charge is placed at a distance z away from the above frame (z

• A.            ? ve charge oscillates along the \[\]axis.
• B.            It moves away from the frame
• C.            It moves slowly towards the frame and stays in the plane of the frame      
• D.            It passes through the frame only once.