What denotes a ten-year service in a specific capacity in the Army?

The correct answer is "Ten-Year Device." This designation specifically recognizes service members who have demonstrated ten years of service in a particular capacity or military occupational specialty (MOS). The Ten-Year Device is typically worn on the service ribbon of the individual, resembling a miniature star or similar symbol, which serves to highlight the dedication and longevity of their service.

In the context of military awards and decorations, each of the other options represents different forms of recognition but do not specifically denote ten years of service in the same capacity. Award clusters are used to indicate subsequent awards of the same medal, numerals are employed to show the number of awards or campaigns, and service stars typically signify campaign participation or additional periods of service within a fluctuating context rather than a specific role for ten consecutive years. The Ten-Year Device directly aligns with the requirement for indicating a decade of service, making it the appropriate choice for this question.