In a DevOps environment, automating functionality testing is the most necessary action to have confidence in the quality of the changes being made. DevOps is a methodology that integrates the development and operations teams and processes, and aims to deliver software products or services faster, more frequently, and more reliably. Functionality testing is a type of testing that verifies that the software product or service meets the functional requirements and specifications, and performs as expected. Automating functionality testing means using tools or scripts to execute the test cases and scenarios, and compare the actual results with the expected results, without human intervention. Automating functionality testing can improve the speed, accuracy, and coverage of the testing process, and it can enable continuous testing and feedback throughout the software development life cycle. The other options are not correct. Preparing to take corrective actions quickly is a good practice in a DevOps environment, as it can help to resolve any issues or defects that may arise during the software delivery process, but it is not the most necessary action to have confidence in the quality of the changes being made. Receiving approval from the change review board is not a common practice in a DevOps environment, as it can slow down the software delivery process and introduce bureaucracy and bottlenecks. Reviewing logs for any anomalies is a useful practice in a DevOps environment, as it can help to monitor and troubleshoot the performance and behavior of the software product or service, but it is not the most necessary action to have confidence in the quality of the changes being made. References: CISSP All-in-One Exam Guide, Eighth Edition, Chapter 6: Security Assessment and Testing, page 700. Official (ISC)2 CISSP CBK Reference, Fifth Edition, Chapter 6: Security Assessment and Testing, page 698.