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.

[EX Q]: Who's performing the halftime show at super bowl 52?
[EX A]: Who's the featured performer performing the halftime show at super bowl 52?

[EX Q]: Which channel in youtube has the most subscribers?
[EX A]: What was the Youtube channel with the most subscribers as of December 23, 2013?

[EX Q]: Who's the lead singer of the doobie brothers?
[EX A]:
Who's the original lead singer of the doobie brothers?