Which of the following is the rank of E-8?

The rank of E-8 corresponds to various titles within the U.S. military, but the most commonly associated rank with E-8 is indeed First Sergeant. A First Sergeant typically serves in a leadership position and is responsible for the welfare, readiness, and discipline of soldiers within a company. The role requires significant experience and leadership capability, as First Sergeants are often the senior enlisted members in units and play a critical role in bridging the gap between enlisted personnel and their officers.

While Master Sergeant and Sergeant Major are also E-8 ranks, they are distinct positions with different responsibilities and roles. For example, a Master Sergeant focuses more on technical proficiency and may not have the same level of administrative responsibilities as a First Sergeant. Therefore, within the context of the question, First Sergeant is the most appropriate title related to the rank of E-8.