Given the task definition and input, reply with output. Given a question and a context passage, generate the answer having the word or phrase from the context passage. Here, the answer should be a shortest continous span from the passage.

Context: The Race to Urga is a musical theatre play, started in 1968 as an adaptation of the Bertolt Brecht play The Exception and the Rule, with the project soon renamed to A Pray by Blecht.
Question: Which is the basis of The Race to Urga?
the exception and the rule