Final answer:
The key reason for keeping test data for automated tests under version control is to ensure reproducibility of the tests, which allows consistent results and aids in audits.
Step-by-step explanation:
One key reason for keeping the test data for automated tests under version control is c) Ensuring reproducibility. Version control allows you to track changes to test data over time. This is critical for ensuring that tests can be repeated with the same data to produce consistent results. Keeping test data under version control also aids in identifying what data was used during a specific test run in the case where a glitch is discovered later or when the test needs to be audited or reviewed.