A spherical capacitor consists of two concentric conducting spherical shells of radii \(a\) and \(b\) (where \(b > a\)) separated by a vacuum. The capacitance of this configuration is given by \(C = 4\pi\varepsilon_0\dfrac{ab}{b-a}\). Let \(d = b - a\) represent the radial separation between the shells. In the limit where \(d \ll a\), which of the following expressions and physical justifications correctly describes the behavior of the capacitance in terms of the inner shell surface area \(A = 4\pi a^2\) and separation \(d\)?