The best design is to use environment-scoped secrets with the same secret name, such as DEPLOY_KEY, in separate environments such as DevCloud and TestCloud. This lets the same reusable deployment logic reference one consistent secret name while the selected environment supplies the correct value. Option A is invalid because GitHub secret names should not be designed around dotted property access, and reusable workflows should not parse secret names dynamically. Option C introduces unnecessary marketplace dependency and weak secret handling. Option D is also wrong because GitHub secrets are opaque strings; ${{ secrets.DEPLOY_KEY.DevCloud }} is not valid secret property access. Reusable workflows can define and receive named secrets through the secrets mapping.