Final answer:
A 15-gun salute is afforded to a Vice Admiral, which is a naval tradition that associates different gun salutes with different ranks.
Step-by-step explanation:
A 15-gun salute is traditionally rendered to Vice Admiral. Gun salutes are a naval tradition used to honor various officers with a different number of guns for each rank. While an Admiral Chester Nimitz was a fleet admiral, a rank that is higher than a vice admiral and would receive a salute with more guns, the specific answer to your question is C. Vice Admiral.