For a study with a significant risk investigational medical device that could optimize the effects...

In device trials,unanticipated adverse device effects (UADEs)must be promptly reported.

21 CFR 812.150(a)(1):“An investigator shall submit to the sponsor and the reviewing IRB a report of anyunanticipated adverse device effectas soon as possible, but in no event later than10 working days after the investigator first learns of the effect.”

In this case,severe burns with blisteringgo beyond the anticipated effect of mild burns listed in the investigational plan. Therefore, it qualifies as aUADEand triggers expedited reporting. Options A, B, and C are too short; the regulation specifically mandates a10 working day maximumtimeframe.

Thus, the correct answer isD (10 working days).