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].

Example input: For four years we have waited expectantly for the pitter patter of tiny paws. Soon, that wait could finally be over. Tian Tian, the UK's only female giant panda, has conceived and could give birth to a cub as early as August. However Edinburgh Zoo, where the pandas live, have warned people 'not to get too excited' as the process is 'extremely complex'. Moreover, on the two previous occasions keepers inseminated Tian Tian - whose name means 'Sweetie' - she has failed to produce a panda cub. She was artificially inseminated again in March this year, but keepers at the zoo say implantation - when a fertilised egg attaches to the uterus - has not yet occurred.Tian Tian has conceived and could give birth to a cub as early as AugustShe has been inseminated twice before but so far failed to produce a cubTian Tian and Yang Guang arrived in 2011 from China to great fanfareOn loan at £600k a year, became first giant pandas to live in UK for 17 years 
 Questions:Under the terms of the agreement any cubs will return to _ at the age of two, the age at which they would normally leave their mother in the wild.
Example output: China
Example explanation: This is a good example. Based on the passage, any cubs will return to China at the age of two
Q: (CNN)Some members of the U.S. Congress may be resisting proposed new sanctions on Iran, but their opposition doesn't seem likely to stop Congress passing legislation on Tehran's nuclear program by the end of March. As one of the negotiators who sat across the table from the Iranians for the past 15 months, though, I can assure you that legislation at this juncture risks undermining a deal that is clearly in the interest of all parties. Fortunately, there now seems to be broad consensus that introducing more sanctions with immediate effect would simply play into the hands of Iranian hard-liners. With that in mind, ideas for moving legislation have turned to focus on two concepts: establishing a "trigger" for new sanctions, linked either to an arbitrary future date or a collapse in the talks, and defining what would constitute a good deal and requiring an "up or down" vote on it.Congress has been discussing whether to impose more sanctions on IranRichard Nephew: Movement of such legislation still risks sparking escalatory cycle 
 Question:Ultimately, there is a role for _ to play, but lawmakers should fulfill their oversight role without being unnecessarily prescriptive and, having set expectations for negotiators already, should leave the exact contours of a deal to our scientists, experts and diplomats.
A:
U.S. Congress