For which purpose would an administrator use AWS Config rules?

An administrator would use AWS Config rules specifically to run checks for security policy compliance. AWS Config provides a service to assess, audit, and evaluate the configurations of AWS resources. With the use of Config rules, administrators can define desired states for their resources and automatically check whether these states meet compliance standards or best practices.

When an AWS resource is non-compliant, Config can alert the administrator or take action in response to the deviation. This capability is essential for maintaining a secure and compliant AWS environment, as it allows organizations to continuously monitor their resource configurations and enforce security policies effectively. By ensuring that resources remain compliant with established security policies, administrators can mitigate potential security risks that could arise from misconfigured resources.

The other options don't align with the specific functions of AWS Config rules. Developing new applications, enhancing personnel training, and addressing network congestion are outside the scope of AWS Config's purpose, which is focused on resource compliance and configuration management.