In the Bohr model of the hydrogen atom, an electron of mass \(m_e\) and charge magnitude \(e\) moves in a circular orbit of radius \(r_n\) around a stationary proton. The electrostatic force provides the centripetal acceleration, and the electron's orbital angular momentum is quantized according to \(m_e v_n r_n = \dfrac{n h}{2\pi}\), where \(n\) is a positive integer and \(h\) is Planck's constant. Which of the following expressions correctly represents the speed \(v_n\) of the electron in the \(n\text{th}\) orbit in terms of \(n\), \(h\), \(e\), Coulomb's constant \(k\), and fundamental constants?