Which statement best distinguishes Quality Control from Quality Assurance in GCP?

• A. QA is performed only by the sponsor; QC by the site
• B. QC focuses on preventing errors; QA focuses on finding errors
• C. QA focuses on preventing problems in the process, QC tests the outputs
• D. They are unrelated concepts

Answer: (C)

In GCP, the difference comes down to process versus product. Quality Assurance is about the systems and procedures that govern how a trial is conducted, with the aim of preventing problems by ensuring processes are well designed, documented, trained, and audited. Quality Control is about the actual outputs of those processes—inspecting and testing the data and records to detect defects after they’re produced.

The best statement reflects that QA’s job is to prevent problems in the process, while QC’s job is to test and verify the outputs. For example, QA would involve validating study procedures, ensuring SOPs are followed, and conducting process audits to catch issues before they affect data. QC would involve activities like source data verification and data cleaning to catch errors in the collected data.

The other options don’t fit because they imply incorrect roles or relationships (for instance, that QA is only done by sponsors, or that QA and QC are unrelated, or that the focus is reversed).