A rocket travels horizontally in deep space where external forces are negligible. At a particular instant, the rocket has total mass \(M\) and moves forward with speed \(v\) relative to an inertial reference frame. The rocket's engine expels exhaust gas backward at a constant speed \(u_{\text{ex}}\) relative to the rocket at a constant mass rate \(R = -\dfrac{dM}{dt}\). Which of the following expressions represents the instantaneous rate of change of the rocket's linear momentum, \(\dfrac{d(Mv)}{dt}\), in the forward direction?