Answer: True
Explanation: Newton's Third Law states that for every action, there is an equal and opposite reaction. In the case of a firing cannon, the action is the cannonball being shot out of the cannon at high speed. The reaction to this action is the recoil of the cannon, which moves backward. The force exerted by the cannon to launch the cannonball forward is matched by an equal force pushing the cannon backward, illustrating Newton's Third Law.