正解:C
The correct configuration for a successful login to router R1 is found in Option C. This option likely includes the necessary login authentication commands and settings that align with the best practices and guidelines provided in the Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR) course. The course emphasizes the importance of proper configuration of network devices for secure and reliable access, which includes setting up appropriate user authentication methods, specifying privilege levels, and ensuring that the login process is secure to prevent unauthorized access.