Two identical thin nonconducting rings, each of radius \(R\) and carrying a uniform positive charge \(+Q\), are fixed parallel to each other with their centers on the \(x\)-axis at \(x = -d\) and \(x = +d\), where \(d < \dfrac{R}{\sqrt{2}}\). The planes of both rings are perpendicular to the \(x\)-axis, and the origin is located midway between them. An electron of charge \(-e\) is constrained to move along the \(x\)-axis under the influence of the electrostatic force from the two rings. Which of the following best describes the qualitative graph of the electric force \(F_x\) exerted on the electron as a function of position \(x\) along the entire axis from \(x = -\infty\) to \(x = +\infty\)?