Final answer:
People standing in line at the post office would represent a casual crowd, which consists of individuals in the same place without significant interaction.
Step-by-step explanation:
According to Turner and Killian (1993), people standing in line at the post office would represent a casual crowd. This type of crowd consists of people who are in the same place at the same time but who aren’t really interacting. In contrast, a conventional crowd would be at a regularly scheduled event, an expressive crowd might be at a funeral, and an acting crowd might engage in a more purposeful activity like a protest.