Final answer:
The best illustration of informal organization is groupings based on factors such as technical ability, seniority, and personal influence, which represent natural, fluid social structures within an organization.
Step-by-step explanation:
Which of the following best illustrates informal organization? The answer is e. Groupings based on such factors as technical ability, seniority, and personal influence. This is because informal organization refers to the more personal and less systematic structures that emerge naturally among people within formal organizations. Unlike formal organization, which is defined by set responsibilities, hierarchy, and official roles, informal organization is usually more fluid and can cut across formal reporting lines. It is based on personal relationships, networks, and group dynamics among the members of the organization.
Informal organization can be contrasted with formal organization elements like line authority in military structures, staff authority in corporate settings, and functional authority over specific areas such as pension plan legality. These examples all relate to officially designated positions and roles that exist within a structured hierarchy and are characteristic of formal organization.