A researcher has her graduate student conduct a study, but does not him the purpose of the study or to which group participants are assigned) In

A researcher has her graduate student conduct a study, but does not him the purpose of the study or to which group participants are assigned) In addition, participants are not informed of the purpose of the study until after the study is complete. This study is an example of?
1) uninformed study
2) pilot study
3) double-blind study?
4) nonresponse study?