Fear can interrupt processes in our brains that allow us to regulate emotions, read non-verbal cues and other information presented to us, reflect before acting, and act ethically. This impacts our thinking and decision-making in negative ways, leaving us susceptible to intense emotions and impulsive reactions.
I'm not 1000% confident in this answer but I believe it's B) to inform readers about the tactics Sparta and Rome used to hold cities and their effectiveness
