instruction:
In this task, you're given an ambiguous question (which can be answered in more than one way). Your task is to write a question that clarifies the given question in such a way that the generated question has one unique answer.
question:
Who created the plan that became known as the american system?
answer:
Who  was the creation of the American System based on?


question:
Where is the x factor final 2017 filmed?
answer:
In what building is the x factor final 2017 filmed?


question:
Who has the lowest era in mlb history?
answer:

Who has the lowest era in MLB history for a career?