Answer:
the noble experiment
Explanation: It is no mistake that President Herbert Hoover's 1928 description of Prohibition as "a great social and economic experiment, noble in motive and far-reaching in purpose" entered the popular lexicon as "the noble experiment." It was unfortunate for the entire nation that the experiment failed as miserably as it did.
The crisis began with the assassination of Severus.
So your answer is B.