Final answer:
The key factor in making a clean kill is accuracy, as it ensures a quick and ethical death. Other factors like speed, stealth, and strength may assist, but precision is paramount for a humane outcome.
Step-by-step explanation:
One key factor in making a clean kill is accuracy. This is important because to make a humane kill, the hunter must be able to hit the target precisely in a vital area that will result in a quick and ethical death. Speed, stealth, and strength may all be beneficial in hunting, but without accuracy, they do not guarantee a clean kill. The quotes provided refer to strategies and maneuvers in warfare, which metaphorically can relate to hunting in terms of making strategic moves (maneuvers direct and indirect) and targeting weaknesses (enemy's weak points). However, in the context of hunting and making a clean kill, the emphasis is on ensuring a single, precise shot.