Which of the following ranks is designated as O-7?

The rank designated as O-7 is Rear Admiral Lower Half. In the United States Navy and other branches of the Armed Forces, military ranks are categorized by pay grades, with 'O' designating officer ranks. O-7 specifically refers to the rank of Rear Admiral Lower Half, which is a one-star admiral. This rank signifies a senior leadership position and is part of the flag officer ranks.

In contrast, the other choices represent different ranks with varying pay grades. Chief Warrant Officer Three is classified as W-3, a warrant officer rank below the officer grades. Vice Admiral corresponds to O-9, which is a three-star rank, and Captain is an O-6 rank within the officer category, which is one rank below Rear Admiral Lower Half. The distinctions among these ranks are important for understanding military hierarchy and command structure.