Which design principle is included in the operational excellence (CLF-C02)

Correct answer: B. Anticipate failure.
The operational excellence pillar of the AWS Well-Architected Framework includes the design principle of "Anticipate failure". This principle emphasizes the importance of designing systems that can gracefully handle failures and disruptions, rather than assuming that everything will always work perfectly.

The other options are not directly associated with the operational excellence pillar:
A. "Create annotated documentation" is more closely related to the reliability pillar.
C. "Ensure performance efficiency" is part of the performance efficiency pillar.
D. "Optimize costs" is part of the cost optimization pillar.

The operational excellence pillar focuses on running and monitoring systems to deliver business value and to continually improve supporting processes and procedures. Anticipating and handling failures is a key aspect of this pillar, as it helps ensure that systems can maintain their intended level of operation even in the face of disruptions.