Explanation
Regression of software is the risk that a change in one part of the software causes a defect in another part of the software that was previously working correctly. Regression of software is a high risk in agile projects because there is code churn due to change in business needs over several sprints. Code churn is the amount of code that is added, modified, or deleted in a software project over time. Code churn can indicate the volatility and complexity of the software, and the frequency and magnitude of the changes. In agile projects, code churn can be high because the business needs and the user requirements can change rapidly and frequently over several sprints, which are short iterations of development and testing. This means that the software is constantly evolving and adapting to the changing needs, and that the existing functionality and quality may be affected by the new or modified code. Therefore, regression of software is a high risk in agile projects, and it requires effective testing strategies and techniques to prevent, detect, and fix the regression defects. References: ISTQB Foundation Level Agile Tester Syllabus1, Section 2.3.2, page 17; ISTQB Glossary of Testing Terms2, version 4.0, pages 36 and 55