Final answer:
The metaphor suggests that Nick's understanding of social dynamics is that groups are chaotic and unpredictable.
Step-by-step explanation:
The metaphor of referring to groups of people as "swirls and eddies" suggests that Nick's understanding of social dynamics is option a. Groups are chaotic and unpredictable.
By comparing groups to swirls and eddies, Nick implies that groups are constantly changing, shifting, and difficult to predict, much like the movements of water in a whirlpool or turbulent river. This metaphor suggests that Nick sees social dynamics as dynamic, complex, and ever-changing.
For example, just as swirls and eddies in water can suddenly change direction or intensity, groups of people can also experience sudden shifts in behavior, mood, and opinions. Nick's use of this metaphor indicates an understanding that social dynamics are not static but rather influenced by various internal and external factors that can lead to unpredictability.