Comprehensive and Detailed Explanation:

In Google’s Site Reliability Engineering (SRE) practices, an error budget defines the acceptable level of failure before new feature deployments should pause. If a service exceeds its error budget, the correct approach is to:

Notify the product team that the error budget is depleted.

Negotiate a launch freeze or decide if the team can tolerate slightly degraded performance.

????Why not other options?

A (Ensure all tests pass and proceed)❌→ Testing cannot guarantee stability when the error budget is already depleted.

C (Request additional error budget)❌→ Error budgets are not arbitrary; increasing them would defeat their purpose.

D (Reallocate SLOs from other areas)❌→ Error budgets should not be mixed across different SLOs, as this breaks reliability guarantees.

????Official Reference:

Google SRE: Error Budget Policy

Google Cloud SRE Principles