An ideal LC circuit consists of an inductor of inductance L and an air-filled parallel-plate capacitor of plate separation d and plate area A, oscillating with maximum charge Q_{\text{max}} and angular frequency \omega. The electrical system is modeled by an analogous mechanical system consisting of a block of mass m oscillating on a frictionless horizontal surface connected to an ideal spring of force constant k. If the plate separation d of the capacitor is doubled while Q_{\text{max}} and L remain constant, which of the following correctly describes the resulting change in the circuit's angular frequency \omega, the change in the maximum magnetic energy U_{B,\text{max}} stored in the inductor, and the analogous modification to the spring constant k in the mechanical oscillator?