Two identical thin rings, each of radius \(R\) and carrying a uniform positive charge \(+Q\), are fixed parallel to each other and centered on a common \(x\)-axis at \(x = -d\) and \(x = +d\), where \(d > R\). Which of the following graphs best represents the electric potential \(V\) along the \(x\)-axis as a function of position \(x\)?