An underwater camera is positioned at a depth \(d\) below the surface of a calm body of water. The index of refraction of the water is \(n\) (where \(n > 1\)), and the index of refraction of the air above the surface is \(n_{\text{air}} = 1\). Light rays originating from the entire sky above the surface enter the water and are refracted, forming a bright circular window of light on the water's surface directly above the camera. Which of the following expressions represents the diameter \(D\) of this circular window?