Final answer:
A command group is exemplified by Ed, the supervisor for a brick-laying team at a construction site, as it involves clear authority and hierarchical structure.
Step-by-step explanation:
An example of a command group can be identified as a group in which the members regularly interact with each other and have stable relationships, and there's a clear hierarchy and chain of command that they follow. Considering the provided options, the correct answer is C) Ed is a supervisor for a brick-laying team at a construction site.
This scenario represents a command group because it typically involves a supervisor who has clear authority over team members who perform specific tasks. Options A, B, and D describe committees, voluntary groups, or informal social gatherings, which do not have the same hierarchical structure or ongoing, formal authority relationships as a command group does.