A spaceship in space sweeps stationary interplanetary dust. As a result, its mass increases at a rate $\frac{dM(t)}{dt} = bv^2(t)$, where $v(t)$ is its instantaneous velocity. The instantaneous acceleration of the satellite is:\\
(1) $-bv^3(t)$\\
(2) $\frac{-bv^3}{M(t)}$\\
(3) $-\frac{2bv^3}{M(t)}$\\
(4) $-\frac{bv^3}{2M(t)}$