Final answer:
The President of the United States is the sole approval authority for Naval decorations to members of the U.S. Public Health Service (USPHS), in his role as Commander in Chief.
Step-by-step explanation:
The sole approval authority for Naval decorations to members of the U.S. Public Health Service (USPHS) is the President of the United States. As outlined in Section 2 of the U.S. Constitution, the President holds the role of Commander in Chief of the Army and Navy, and by extension, has command over the commissioned corps of the USPHS, which falls under the Department of Health and Human Services. The transformation from the Marine Hospital Service to what is now known as the USPHS Commissioned Corps demonstrates this executive responsibility. Hence, the President has the power to grant honors and decorations relating to service within these bodies, in line with his executive powers to lead the military and manage affairs relating to national defense and security.