Which of the following is not a designation for any enlisted pay grade?

In the context of enlisted pay grades in the Navy, the correct designation that is not associated with an enlisted pay grade is "Admiral." This title refers to a high-ranking officer in the Navy and is part of the officer pay grades rather than the enlisted ranks. Enlisted personnel have specific titles reflecting their ranks, which include Seaman Recruit, Seaman Apprentice, and Seaman. Each of these represents different stages within the enlisted ranks and determines the responsibilities and pay associated with that rank. In contrast, "Admiral" signifies a senior management role and is not applicable to enlisted personnel. Understanding the distinction between enlisted ranks and officer ranks is crucial for recognizing the structure and hierarchy within the Navy.