Which one of these responsibilities does not belong to the Coast Guard?

The responsibility that does not belong to the Coast Guard is the regulation of the rates and practices of shipping lines. The Coast Guard primarily focuses on maritime safety, security, and environmental protection, which includes activities such as pollution control, preventing crimes or sabotage related to ports, and conducting search and rescue missions.

While the regulation of shipping lines does involve oversight of maritime operations, it typically falls under the jurisdiction of different regulatory bodies, such as the Federal Maritime Commission in the United States. The Coast Guard’s mission is more operational and enforcement-based, focusing on promoting maritime safety and security rather than regulating commerce. Thus, the other options accurately reflect the Coast Guard's core responsibilities.