【单选题】The Declaration of Helsinki (2013, Article 33) by WMA declares that, "The benefits, risks, burdens and effectiveness of a new intervention must be tested against those of the best proven intervention(...
A.
Where no proven intervention exists, the use of placebo, or no intervention, is acceptable; or
B.
Where for compelling and scientifically sound methodological reasons the use of any intervention less effective than the best proven one, the use of placebo, or no intervention is necessary to determine the efficacy or safety of an intervention and the patients who receive any intervention less effective than the best proven one, placebo, or no intervention will not be subject to additional risks of serious or irreversible harm as a result of not receiving the best proven intervention. Extreme care must be taken to avoid abuse of this option.