Which member of the trial team is designated and supervised by the investigator at the trial site to perform critical trial-related procedures and/or to make important trial-related decisions?

• A. Sponsor
• B. Sponsor-Investigator
• C. Standard Operating Procedures (SOPs)
• D. Subinvestigator

Answer: (D)

In GCP, the person who is designated by the investigator at the trial site to carry out essential trial-related procedures and to make important trial-related decisions, under the investigator’s supervision, is the subinvestigator. This role exists to support the investigator with hands-on tasks that require clinical expertise and judgment, while ultimately remaining accountable to the investigator. The subinvestigator is distinct from the sponsor (the party funding and overseeing the study) and from a sponsor-investigator (someone who fulfills both sponsor and investigator duties). SOPs, on the other hand, are the documented procedures guiding how work is done, not people. So the subinvestigator fits the description perfectly because it is a designated, supervising role focused on performing critical procedures and decisions on behalf of the investigator.