Comprehensive and Detailed Explanation From Exact Extract:

When a team exceeds its error budget, SRE practice requires applying error budget policies that restrict feature releases and shift focus toward reliability improvement. The idea is to prevent further degradation of user experience and ensure the service meets the agreed reliability targets.

The Site Reliability Engineering Book, Chapter “Service Level Objectives,” states:

“If the service exceeds its error budget, all new feature launches or risky changes are halted until reliability returns to acceptable levels. Engineering work should be directed toward addressing the causes of the budget overrun.”

This aligns with option A, which describes a reliability-focused response during sprint planning. Limiting sprint planning to post-mortem action items and reliability improvements is a direct application of error budget policies.

Additional guidance from the SRE Workbook:

“Error budget burn should directly influence decision-making. When the budget is exhausted, the team must focus on remediation work rather than new features.”

Why the other options are incorrect:

B Reviewing the error budget’s realism can be done periodically, but it is not the immediate consequence of a breach.

C Extending the error budget invalidates its purpose and is discouraged.

D Ignoring the error budget contradicts the entire SRE model and Google’s official guidance.

Therefore, A is the only correct answer.