During the course of administration of an investigational drug, the following events occurred: on day 7, subject 603 had an unexpected stroke that requires hospitalization; on day 15, subject 415 complained of nausea, vomiting, and headache relieved by aspirin; on day 21, subject 20 has brief dizzy spells upon trying to stand. which of these subject’s events meets the fda definition of "serious" and "unexpected" and would require the sponsor to file an ind safety report with the fda?