GitHub Actions routes jobs to self-hosted runners by using runner labels. Custom labels representing required capabilities, such as the operating-system version and Xcode version, can be created and assigned to the appropriate runner. The workflow then specifies those labels in runs-on. When multiple labels are supplied, GitHub requires an eligible runner to match all specified labels, so runs-on: [self-hosted, macos-10.15, xcode-11.2] targets the intended runner configuration. Runner groups are primarily an access-control and organizational mechanism and are not represented by the ${{ groups.* }} expression shown in option B. The Xcode/macOS versions in this exam scenario are historical, but the runner-label routing principle remains current. GitHub documentation confirms custom labels and cumulative runs-on label matching.

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