An artillery piece of mass \( M_1 \) fires a shell of mass \( M_2 \) horizontally. Instantaneously after the firing, the ratio of kinetic energy of the artillery and that of the shell is:
\( \dfrac{M_2}{M_1 + M_2} \)
\( \dfrac{M_1}{M_1 + M_2} \)
\( \dfrac{M_2}{M_1} \)
\( \dfrac{M_1}{M_2} \)