Detailed Explanation
The investigator bears primary responsibility for the conduct of a clinical trial at their site, including the protection of the rights, safety, and well-being of all participants enrolled under their supervision. This role demands both scientific expertise in the relevant therapeutic area and thorough understanding of Good Clinical Practice requirements. When a trial is conducted by a team, the individual who serves as the responsible leader of the team is designated as the principal investigator, while other qualified physicians and professionals are termed sub-investigators and work under the principal investigator's oversight.