Which item is the primary document used to record data collected in a clinical trial?

• A. Input Screen Design
• B. Output Screen Design
• C. Data Type
• D. Source Document

Answer: (D)

In a clinical trial, data first exist in source documents—the original records where measurements, observations, and events are documented, such as patient charts, lab reports, or clinician notes. This makes the source document the primary record of data collected, since it preserves the original information before it is transferred into a case report form or an electronic data capture system for analysis. The other options focus on how data are entered or displayed or on data classification, not on where the data originated. Understanding this helps ensure data integrity and traceability, because auditors verify that the data in the study records match what’s in the source documents.