What is the rank of an officer who wears shoulder boards with 4 silver five-pointed stars?

The rank of an officer who wears shoulder boards with 4 silver five-pointed stars is indeed the Admiral rank. In the United States Navy, an Admiral is a four-star officer, and the four stars are a clear indication of this rank. The shoulder boards worn by an Admiral prominently display these four stars, signifying their senior leadership position within the Navy hierarchy.

Fleet Admiral, which is a higher rank, is reserved for the highest-ranking naval officers and is represented by five stars, making it distinct from the Admiral rank. Rear Admiral Upper Half also has two stars, and Vice Admiral has three, which further clarifies that an officer with four stars corresponds specifically to the Admiral rank. Each level of rank in the Navy is defined by these insignia, and the presence of four silver stars directly denotes the Admiral rank, thus making it the correct choice in this context.