For a tachometer, if \(\theta(t)\) is rotor displacement in radians, \(e(t)\) is the output voltage and \(k_{t}\) is the tachometer constant in V/rad. \(\mathrm{sec}^{-1}\), then the transfer function \(\mathrm{E}(\mathrm{s}) / \theta(s)\) will be
(a) \(k_{t} s^{2}\)
(b) \(k_{t} / s\)
(c) \(k_{t} s\)
(d) \(k_{t}\)