Detailed
The issue could have been avoided if the developer had used Sandbox testing (Option D), which allows new software to be tested in a controlled environment before implementation. This process ensures that the software does not negatively impact system functionality, like stopping access to critical resources such as file servers.
End-user acceptance (Option A) ensures that users approve the software, but it wouldn't prevent the issue.
Staff delegation (Option B) relates to who is responsible but doesn't address testing.
Appropriate scoping (Option C) helps in defining the extent of changes but does not replace testing.
CompTIA A+ Core 2 Reference:
4.2 - Explain basic change management best practices, including testing in a sandbox environment.