A machine gun fires 120 shots per minute. If the mass $o$ each bullet is $10 \mathrm{~g}$ and the muzzle velocity is $800 \mathrm{~m} / \mathrm{sec}$ the average recoil force on the machine gun is:
(a) $120 \mathrm{~N}$
(b) $8 \mathrm{~N}$
(c) $16 \mathrm{~N}$
(d) $12 \mathrm{~N}$.