Which of the following is a primary duty of the Coast Guard?

The primary duty of the Coast Guard includes the interdiction of illegal drug trafficking at sea, which falls under its role in ensuring maritime safety and security. The Coast Guard protects the nation's waters and enforces maritime law, including the suppression of drug smuggling operations that threaten national security and public safety. This mission is critical in combating drug-related crime and protecting coastal communities from the harmful effects of illegal drug trafficking.

In contrast, the Coast Guard does not manage the Navy's operational readiness, conduct air strikes on enemy territories, or organize Navy's overseas operations, as those responsibilities primarily lie within the purview of the Department of Defense and the Navy itself.