Which of the following positions indicates that a sailor is at ease while in formation?

The position that indicates a sailor is at ease while in formation is a relaxed stance. This posture demonstrates a level of comfort and informality in a situation where a sailor would typically be required to assume a more rigid posture, such as standing tall with feet together and hands clasped behind the back. A relaxed stance allows for a more casual, yet respectful, display while maintaining an awareness of the overall formation's discipline.

While other options like standing tall or having feet together suggest a state of attention or readiness, they do not convey the ease that the correct answer does. In contrast, a relaxed stance embodies the idea of being at ease in formation, reflecting a balance between being casually comfortable and retaining a sense of military decorum.