A developer needs a reversible feature rollout without deploying a new binary for each percentage change. The application can poll managed configuration. Which service feature is a suitable fit?

1. AWS AppConfig feature flags with suitable validation, deployment strategy, and monitoring.
2. Enable the feature permanently for all users before observing any metrics.
3. Use an IAM policy description as the only runtime feature-state source.
4. Hard-code the enabled state in every client and redistribute the application for each change.