The figures below depict two situations in which two infinitely long static line charges of constant positive line charge density $\lambda$ are kept parallel to each other. In their resulting electric field, point charges $q$ and $-q$ are kept in equilibrium between them. The point charges are confined to move in the x-direction only. If they are given a small dispacement about their equilibrium positions, then the correct ststement(s) is (are) :