Refactoring a monolith into microservices: which design aspects should you implement? (Choose two.)

Creating an API contract between each microservice and its callers is crucial because it defines the expected input, output, and behavior of the service, enabling independent development and deployment. This contract acts as a stable interface, preventing breaking changes and ensuring interoperability. While ensuring enough instances for performance is important for operational readiness, it's a deployment and scaling concern, not a core design aspect of refactoring a monolith into microservices. Developing each microservice in the same programming language as its caller defeats a key benefit of microservices, which is technology independence. Requiring asynchronous communication for all interactions is overly restrictive; synchronous communication is appropriate in many scenarios. Implementing API versioning is a good practice for managing change, but the API contract itself is the fundamental design element that defines the interaction.