Which form does a YN prepare upon receipt of a promotion message?

The correct form that a Yeoman (YN) prepares upon receipt of a promotion message is NAVPERS Form 1421/7. This form is specifically designated for the processing of officer and enlisted promotions, capturing essential details such as the member's new rank, the effective date of promotion, and other necessary documentation related to the promotion process. It ensures that the promotion is officially recorded and communicated within the appropriate channels.

The other forms listed serve different purposes. For instance, NAVPERS Form 1010/6 pertains to administrative actions that are not specifically related to promotions. NAVPERS Form 1366/5 is utilized for other personnel matters, and NAVPERS Form 1500/8 relates to different administrative functions within the personnel management realm. Thus, forms B, A, C, and D are not aligned with the promotion process, which reinforces why NAVPERS Form 1421/7 is the correct choice for this situation.