In this task, you will be presented with a passage and have to answer a question based on your understanding of the events inferred from the passage. Try to find the best answer that is most likely to fill in "_". Note that the URLs in the text have been replaced with [Link].

Q: Washington (CNN) Ohio Democratic Rep. Tim Ryan is calling his bid to oust Nancy Pelosi a "David versus Goliath" type clash -- a back bencher competing against the top House Democrat who made history in 2007 when she was sworn in as the first female speaker of the House. "If you're a quarterback and you keep throwing interceptions, you change quarterbacks," the 43-year-old Ryan, a former high school football player, said in a recent interview criticizing the record of Pelosi, 76, and arguing it's time for a younger generation to take the reins. Ryan's gambit is unusual because most leadership challenges come from members using another party position or a top slot on a key committee as a launching pad.Ryan is in his 7th term, but hasn't been a national leader for DemocratsYounger Democrats are unhappy with the lack of opportunities to advance in party leadershipPelosi is expected to fend off Ryan's challenge 
 Question:Ryan and other _ who pressed for more time before the vote point out that there is basically no bench for House Democrats.

A: Democratic
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Q: Moscow (CNN) -- Russia's upper house of parliament voted Wednesday to revoke the right of President Vladimir Putin to use troops in Ukraine as efforts continue to calm a separatist uprising in Ukraine's east. The Federation Council had approved Putin's request for a resolution allowing the use of force on March 1. But Tuesday, Putin sent a letter to the speaker of the upper house seeking to cancel the resolution. One lawmaker voted against revoking the powers Wednesday, with 153 in favor. Putin's request was made in light of ongoing talks on how to settle the crisis in Ukraine's eastern regions, said presidential spokesman Dmitry Peskov.NATO agrees to a package of support to help Ukraine defend itselfRussia's Federation Council cancels resolution authorizing use of troops in UkrainePresident Vladimir Putin asked for the step in light of peace talks, his spokesman saysJohn Kerry and other NATO foreign ministers are meeting in Belgium 
 Question:The parliamentary action is a positive step, _ said, but it could be easily reversed.

A: John Kerry
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Q: A wave of migrants 4,500 years ago left their trace in the DNA and languages of modern Europeans. This is according to a study that found evidence of this Stone Age migration by analysing DNA of 69 people who lived across Europe between 8,000 and 3,000 years ago. Among the shifts in the genetic make-up of ancient Europeans they found that DNA associated with the Yamnaya people appeared strongly in what is now northern Germany. Researchers have identified a mass migration of Kurgan populations (Yamna culture) which went from the Russian steppes to the centre of Europe 4,500 years ago. Previously, researchers had believed it spread 8,500 years ago, when the first farmers from the Near East, now modern day Turkey, brought it to EuropeStudy looked at DNA of Europeans who lived 8,000 and 3,000 years agoDNA associated with Yamnaya people appeared in northern GermanyYamnaya were herders from the steppe north of the Black and Aral SeasThis suggests a large influx that would have changed speech and DNAPreviously, researchers believed that Indo-European language spread some 8,500 years ago, by the first farmers from the Near East, now Turkey 
 Question:There are two main theories as to how Indo-European languages spread in _.

A:
Europeans
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