The other bank of the stream was open ground -- a gentle slope topped with a stockade of vertical tree trunks, loopholed for rifles, with a single embrasure through which protruded the muzzle of a brass cannon commanding the bridge.
What is the BEST meaning of the word muzzle as it is used in this sentence?
A) a leather or wire restraining appliance
B) a restraint on free movement or expression
C) the forward discharging end of the barrel of a firearm
D) the forward projecting part of the head of certain animals