Which of the following is not a type of crowd?

The correct choice reflects the classification of crowds typically recognized in social and psychological studies. Picketing is an organized form of protest, which doesn't fit the broader categories of crowd types based on characteristics of their behavior and cohesion.

Casual crowds are composed of individuals who come together without a specific intent or organization, often gathered by chance or curiosity. Expressive crowds, on the other hand, gather to share emotions or to express feelings about a certain issue, showcasing a specific collective emotional state. Cohesive crowds are characterized by a strong sense of unity and purpose among the individuals present, often driven by a shared goal or identity.

Picketing, while it involves a group of people, is more about a specific action undertaken to signal dissent or influence behavior, rather than fitting the general types of crowds based on their inherent characteristics and dynamics. Thus, it stands out as not being a typical category of crowd in the context of social science classifications.