Which of the following is NOT a rank classified as E-8?

The rank of Corporal is not classified as E-8, making it the correct answer to this question. In the United States military, the E-8 ranks include Master Sergeant, Sergeant Major, and First Sergeant, all of which are higher enlisted ranks involved in leadership and operational roles. Corporal, by contrast, is classified as an E-4 rank, which is notably lower in rank and typically considered a junior leadership position. Thus, Corporal does not meet the criteria of being an E-8 rank, distinguishing it clearly from the other options listed.