Which One of the Following Experiments Would Be Considered Acceptable

Which one of the following experiments would be considered acceptable in our society?

A) Determining the effects of cocaine use on babies born to cocaine-using mothers.
B) Determining the response of a patient's "incurable" cancer to a newly developed cancer drug.
C) Testing the effects of radiation exposure on volunteers.
D) Testing the effectiveness of a new AIDS vaccine using deliberate exposure of human volunteers to HIV.
E) Testing the effectiveness of a newly developed antibiotic using deliberate exposure of humans to antibiotic-resistant bacteria.