Final answer:
The Fifth Fleet is the fleet subordinate to the US Naval Forces Central Command, with a responsibility for security and navigation in critical waterways in its region.
Step-by-step explanation:
The fleet that is subordinate to the US Naval Forces Central Command is the Fifth Fleet. The Fifth Fleet is responsible for naval forces in the Persian Gulf, Red Sea, Arabian Sea, and parts of the Indian Ocean. This fleet plays a strategic role in regional security and ensuring the free flow of commerce through some of the world's most critical waterways, including the Strait of Hormuz and the Suez Canal.