Answer:
3). No, this does not need to be reported since it is unrelated to participation in the study.
Explanation:
As per the question, the given event must not be reported to IRB as 'the subject's heart attack, hospitalization, or recovery is not affiliated to his/her participation in the study'. The study aimed to assess the subject's attitudes towards hygiene or disease prevention which has no relation to a sudden heart attack of any of the subject. Thus, this would neither affect the results of the study nor its validity and hence, option 3 is the correct answer.