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].
One example is below.
Q: 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.
A: China
Rationale: This is a good example. Based on the passage, any cubs will return to China at the age of two
Q: (CNN) So the recent report from the Midwest Medical Examiner's Office made it official -- Prince Rogers Nelson died in his residence April 21, 2016, from an accidental overdose of the prescribed opioid, fentanyl. He was 57. In the aftermath of the death of such an iconic figure we are experiencing a flurry of political activity as our elected leaders, both Republican and Democrat, hurry to pass some form of legislation that will help stem the tide of opioid-related death that claimed the lives of some 165,000 Americans from 2000-2014. Most of the proposals debated last week in Washington -- including the compromise package the House approved Friday -- aim at improving access to treatment for those who are already addicted.Chris Johnson says opioid addiction is rampant in U.S. Why?He says to grow market, pharmaceutical companies began pressing doctors to prescribe opioids for chronic painJohnson: Doctors, medical industry needs to focus more on 'patient outcome,' not 'patient experience' 
 Question:By now, you know that the _ consumes 80% of the world's opioid painkillers while comprising just 5% of the world's population.
A:
U.S.