Generate a question which can yield the answer mentioned in the input. Generated question must be answered by the answer provided in input, without using any extra knowledge.

Q: Context : Having suffered for at least a year, Mary Tighe endured a serious attack of tuberculosis in 1805. 
Answer : tuberculosis

A: What was Mary Tighe's medical condition near the end of his life?
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Q: Context : NordStar was founded by Norilsk Nickel and was launched on 17 December 2008, based on local Taimyr Peninsula airlines. 
Answer : Norilsk Nickel

A: Which company is the parent company of NordStar?
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Q: Context : XBEL, or the XML Bookmark Exchange Language, is an open XML standard for sharing Internet URIs, also known as bookmarks (or favorites in Internet Explorer). 
Answer : XML

A:
The XBEL is based upon what?
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