The correct answer is C. Source code version control.

When multiple developers make frequent and simultaneous code changes, the most effective control is source code version control. Version control allows the organization to track changes, manage branches, merge code, identify conflicts, restore prior versions, and maintain accountability for who changed what and when.

Option A is not the best answer because architecture reviews help ensure design alignment, but they do not manage simultaneous file edits. Option B is not the best answer because source code composition scanning identifies third-party/open-source component risks, licensing issues, or known vulnerabilities, but it does not control concurrent code changes. Option D is not correct because CSAs may help teams assess controls, but they do not technically manage code versions.

This question maps to Information Systems Acquisition, Development and Implementation, because ISACA’s CISA Exam Content Outline includes system development methodologies, development controls, implementation testing, and change management-related practices.