Final answer:
According to the social psychology definition by Cartwright and Zander (1968), the best example of a group is coworkers collaborating on a team project.
Step-by-step explanation:
According to the social psychology definition by Cartwright and Zander (1968), the best example of a group would be b) Coworkers collaborating on a team project. Social psychologists believe that a person's behavior is influenced by who else is present in a given situation and the composition of social groups. In this example, the coworkers are actively working together towards a common goal, demonstrating the concept of a group as defined by social psychology.