An object of mass \(m\) is released from rest at time \(t = 0\) in a uniform gravitational field of magnitude \(g\). As the object falls vertically downward, it experiences a resistive drag force of magnitude \(F_{\text{drag}} = bv\), where \(b\) is a positive constant and \(v\) is the speed of the object. Which of the following expressions correctly gives the speed \(v(t)\) of the object as a function of time \(t\)?