Final answer:
The subdivision of the autonomic nervous system associated with the "fight or flight" response is the sympathetic division.
Step-by-step explanation:
The subdivision of the autonomic nervous system most associated with the "fight or flight" response is the sympathetic division. When faced with a threatening or stressful situation, the sympathetic division prepares the body for action by increasing heart rate, dilating the pupils, and initiating the release of adrenaline. These physiological changes enable the body to respond quickly and effectively to potential danger.