How does an API Gateway facilitate a 'Canary Release' strategy for a new version (v2) of a microservice?

1. A It automatically clones the entire production database into a separate v2 database for the test.
2. B Weighted Routing: It routes a small, configurable percentage (e.g., 5%) of traffic to v2 while keeping 95% on the stable v1, monitoring for errors before proceeding.
3. C It ensures that only users with 'Canary' in their username are allowed to use the new service.
4. D It blocks all traffic to v1 to force users to use v2, ensuring the new version is 'battle-tested'.