Explain the role of 'Code scanning alerts' in pull request reviews.

• A. Code scanning alerts on PRs annotate test results
• B. Code scanning alerts disable certain PR checks
• C. Code scanning alerts limit review comments
• D. Code scanning alerts on PRs highlight issues introduced by changes, guiding reviewers to fix defects before merging

Answer: (D)

Code scanning alerts in pull request reviews are there to surface issues that your changes might introduce. When a PR is created, code scanning tools analyze the modified code (often by comparing it to the base branch) and flag potential defects, security vulnerabilities, or quality problems tied to those specific changes. The alerts appear alongside the diff with clear pointers to the exact file and line, usually with a severity level and suggested fixes. This helps reviewers zero in on problems that are newly introduced by the PR, so they can request fixes before merging and reduce the chance of letting defects slip into main.

These alerts are not about test results, nor do they disable PR checks or limit how reviewers can comment. They are a focused signal that guides the review toward the most relevant, introduced issues, improving the safety and quality of the code that gets merged.