An electron of mass \(m_e\) and charge magnitude \(e\) orbits a stationary proton of charge \(+e\) in a circular path. According to the Bohr model of the hydrogen atom, the electron's orbital angular momentum is quantized such that \(L = \dfrac{n h}{2 \pi}\), where \(n\) is a positive integer and \(h\) is Planck's constant. The electrostatic force between the proton and electron provides the required centripetal force. Which of the following expressions correctly represents the orbital radius \(r_n\) of the electron in the \(n\text{-th}\) energy level in terms of \(n\), \(h\), \(m_e\), \(e\), and the Coulomb constant \(k\)?