Which of the following is NOT a role of a petty officer in the Navy?

The role of a petty officer in the Navy encompasses various responsibilities primarily focused on leadership, training, and operational management. Supervising enlisted personnel, instructing junior sailors, and managing day-to-day operations are integral parts of a petty officer's duties. They serve as the first line of leadership, ensuring that junior personnel are developed and that operations run smoothly.

However, conducting formal military investigations is a specialized task that typically falls under the purview of certain command-level personnel or designated investigative officers, rather than the general responsibilities of a petty officer. Petty officers may be involved in supporting investigations or may collect initial information, but they do not generally conduct formal investigations as part of their everyday duties. This distinction clarifies why the task of conducting formal military investigations is not typically associated with the role of a petty officer, making it the correct answer in this context.