The correct answers are Define the application as code to express the desired state, Continuously observe application health and performance, Use a reconciliation loop to detect drift and apply corrective actions, and Automatically adjust resources based on traffic using autoscaling.

Define the application as code to express the desired state is important because declaring the desired state makes the system auditable and reproducible and it lets controllers and automation know what to maintain over time. Continuously observe application health and performance is required so that the system can detect failures and performance regressions and provide the signals needed for corrective actions. Use a reconciliation loop to detect drift and apply corrective actions describes the controller pattern that compares actual state to desired state and then takes actions to return the system to the desired state. Automatically adjust resources based on traffic using autoscaling ensures the application can handle variable load and recover capacity quickly without manual intervention.

Rely on manual configuration changes and one off fixes is incorrect because manual changes are slow and error prone and they do not provide a reliable way to maintain the intended state over time or to recover automatically from faults.

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