Final answer:
The majority of CRF data are verified against source records during Data Monitoring, an essential step in ensuring data accuracy in clinical trials.
Step-by-step explanation:
The process of verifying the majority of case report form (CRF) data against source record information is best described as Data Monitoring. This is an essential step in clinical trials, where accuracy and completeness of data are paramount. During data monitoring, data entered into the CRFs are checked against original records such as hospital files, laboratory results, or clinicians' notes to ensure the data's accuracy and consistency. This step typically occurs after data entry and before data validation and analysis.