What does Azure API Management's policies feature allow you to do?

Azure API Management's policies feature is instrumental in managing how your APIs behave. It allows you to modify API requests and responses, which is crucial for implementing transformations, validations, and error handling. This enables developers to ensure that APIs conform to client expectations, regardless of how the backend services are structured.

Moreover, with policies, you can add cross-cutting concerns such as authentication, logging, caching, and throttling directly at the API gateway level. This means that you can implement features like rate limiting or IP filtering without changing your backend code. The flexibility offered by policies allows teams to manage their APIs in a more agile manner, enhancing performance, security, and usability without tightly coupling these concerns to application logic.

The other options touch upon important aspects of API management as well, like performance monitoring, security measures, and scaling resources. However, those functionalities are typically handled through different features of Azure API Management or require separate configurations outside of the policy framework, which makes the modification of API requests and responses the most suitable answer in the context of policies.