Comprehensive and Detailed Explanation From Exact Extract:

Error budgets represent the allowable amount of unreliability in a system. Google defines the purpose of error budgets as: “balancing the pace of innovation with the need for reliability.” (SRE Book – Service Level Objectives). When the error budget is healthy, product teams can release features quickly; when it is exhausted, reliability work takes priority. This balance prevents over-investment in reliability and enables safe innovation.

Option B—innovation and reliability—is the exact phrasing used in Google’s SRE literature.

Options A, C, and D do not reflect the core purpose of error budgets.

Thus, B is the correct answer.