TASK DEFINITION: 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].
PROBLEM: Washington (CNN) North Korea might not be able to reach the U.S. mainland with a nuclear weapon yet, but the political fallout from its claimed hydrogen bomb test is here already. Even before the shockwaves of the 5.1 temblor triggered by Tuesday's test wore off, Hillary Clinton was fighting off a volley of Republican attacks, GOP presidential candidates were talking tough and Donald Trump jumped on a chance to chastise China. The episode was a fresh indication of the challenge that Clinton faces in running for the White House on her record as secretary of state, which makes it impossible for her to escape deficiencies in President Barack Obama's national security legacy.The episode is a fresh indication of the challenge that Clinton faces in running for the White House on her record as secretary of stateWashington has tried punishment and inducements repeatedly with North Korea and has failed to change its calculations 
 Question:He then toughened his stance by including _ in his "axis of evil."

SOLUTION: North Korea

PROBLEM: Da Nang, Vietnam (CNN) President Donald Trump suggested on Saturday he's done confronting Russian President Vladimir Putin over his country's election meddling since it's insulting to the Russian leader. Trump said he took Putin at his word that Russia did not seek to interfere in the US presidential election last year, despite a finding from US intelligence agencies that it did. The fraught relations between the two leaders was underscored anew when Putin's spokesman initially said election meddling did not come up when they spoke, even though Trump said it did. And he stressed that bigger issues persist between the United States and Russia that require the two leaders to move on."He said he didn't meddle," Trump saidTrump spoke to reporters aboard Air Force One in Vietnam 
 Question:As _ has traveled abroad, the special counsel investigation looking into possible collusion between his campaign aides and Russia has crept closer to Trump's inner circle.

SOLUTION: Donald Trump

PROBLEM: LONDON, England (CNN) -- There is a mathematical reason why the French Open is so different to any other of the Grand Slam tennis tournaments. Clay courts require a different type of game to grass and hard court surfaces The Roland Garros tournament is currently being contested, with Rafael Nadal looking for his fifth win in a row, and world number two Roger Federer searching for his first ever French Open title. • Get the latest French Open news What has brought problems to Federer, and to other greats like Pete Sampras and Boris Becker -- who never won a French Open, is the clay surface on which it is contested.Clay, grass and hard tennis court surfaces all produce different bouncesThe speed and bounce of certain courts can adversely affect a player's gameUse the CNN interactive to see how the bounce differs on each surface 
 Question:One of the problems _ has on clay is that he has a single-handed backhand, and Nadal can get so much spin -- so Federer is trying to hit single-handed shots up around his shoulder."

SOLUTION:
Roger Federer