What must a clinical trial comply with?

• A. The protocol that received prior IRB/IEC approval.
• B. The sponsor's internal marketing plan.
• C. The investigator's personal preferences.
• D. None of the above.

Answer: (A)

The essential requirement is to conduct the trial strictly according to the protocol that was approved by the IRB/IEC and in line with applicable regulatory requirements. The protocol is the detailed plan for how the study will be done, including objectives, design, procedures, and data collection. Following it protects participant safety and ensures the reliability of the data. If changes are needed, they must be reviewed and approved through the proper channels before implementation, and informed consent must reflect any modifications. A sponsor’s internal marketing plan is not a basis for trial conduct, and the investigator should not let personal preferences override the approved protocol.