Definition: In this task, you're given a context passage, followed by a question that needs to be answered. Based on the paragraph, you must write unambiguous answers to the questions and your answer must refer to a specific phrase from the paragraph. If multiple answers seem to exist, write the answer that is the most plausible.

Positive Example 1 -
Input: Tracy slept awkwardly on their new bed and was having some pain, so Tracy cracked her neck. 
Question: What did Tracy do with her neck?
Output: crack her neck

Positive Example 2 -
Input: The story of the rise of politician Willie Stark from a rural county seat to the governor's mansion is depicted in the film. He goes into politics, railing against the corruptly run county government, but loses his race for county treasurer, in the face of unfair obstacles placed by the local machine. Stark teaches himself law, and as a lawyer, continues to fight the local establishment, championing the local people and gaining popularity. He eventually rises to become a candidate for governor, narrowly losing his first race, then winning on his second attempt. Along the way he loses his innocence and becomes as corrupt as the politicians he once fought against. When his son becomes paralyzed following a drunk driving accident that kills a female passenger, Stark's world starts to unravel and he discovers that not everyone can be bought off. The story has a complex series of relationships. All is seen through the eyes of the journalist, Jack Burden, who admires Stark and even when disillusioned still sticks by him. Stark's campaign assistant, Sadie is clearly in love with Stark and wants him to leave his wife, Lucy. Meanwhile, Stark philanders and gets involved with many women, taking Jack's own girlfriend, Anne Stanton, as his mistress. When Stark's reputation is brought into disrepute by Judge Stanton (Anne's uncle), he seeks to blacken the judge's name. When Jack finds evidence of the judge's possible wrongdoing, a quarter century earlier, he hides it from Stark. Anne gives the evidence to Stark, who uses it against her uncle, who immediately commits suicide. Anne seems to forgive Stark, but her brother, the surgeon who helped save Stark's son's life after the car crash, cannot. The doctor eventually assassinates Stark after Stark wins an impeachment investigation. The doctor in turn is shot down by Sugar Boy, Stark's fawning assistant. The main plot is a thinly disguised version of the rise of real-life 1930s Louisiana Governor, Huey Long, Long's efforts to blacken the name of Judge Benjamin Pavy, and Long's assassination by the Judge's son-in-law (compared to nephew, as in the film), Dr. Carl Weiss. 
Question: What happened to Willie Stark's son?
Output: He was paralyzed in a drunk driving accident.

Negative Example 1 -
Input: tracy wanted to feel safe so she decided to walk behind addison. 
Question: What will happen to Tracy?
Output: appreciate addison

Negative Example 2 -
Input: Tracy told Ash they needed glasses then they accompanied them to the optician for their appointment. 
Question: What does Tracy need to do before this?
Output: know Ash well

Now complete the following example -
Input: In 1939, Martin Kamen and Samuel Ruben of the Radiation Laboratory at Berkeley began experiments to determine if any of the elements common in organic matter had isotopes with half-lives long enough to be of value in biomedical research. They synthesized 14C using the laboratory's cyclotron accelerator and soon discovered that the atom's half-life was far longer than had been previously thought.  This was followed by a prediction by Serge A. Korff, then employed at the Franklin Institute in Philadelphia, that the interaction of thermal neutrons with 14N in the upper atmosphere would create 14C. It had previously been thought that 14C would be more likely to be created by deuterons interacting with 13C. At some time during World War II, Willard Libby, who was then at Berkeley, learned of Korff's research and conceived the idea that it might be possible to use radiocarbon for dating.In 1945, Libby moved to the University of Chicago where he began his work on radiocarbon dating. He published a paper in 1946 in which he proposed that the carbon in living matter might include 14C as well as non-radioactive carbon. Libby and several collaborators proceeded to experiment with methane collected from sewage works in Baltimore, and after isotopically enriching their samples they were able to demonstrate that they contained 14C. By contrast, methane created from petroleum showed no radiocarbon activity because of its age. The results were summarized in a paper in Science in 1947, in which the authors commented that their results implied it would be possible to date materials containing carbon of organic origin.Libby and James Arnold proceeded to test the radiocarbon dating theory by analyzing samples with known ages. For example, two samples taken from the tombs of two Egyptian kings, Zoser and Sneferu, independently dated to 2625 BC plus or minus 75 years, were dated by radiocarbon measurement to an average of 2800 BC plus or minus 250 years. These results were published in Science in 1949.  Within 11 years of their announcement, more than 20 radiocarbon dating laboratories had been set up worldwide. In 1960, Libby was awarded the Nobel Prize in Chemistry for this work. 
Question: What are the last names of the people who, within 11 years of their announcement, more than 20 radiocarbon dating laboratories had been set up worldwide?
Output: 


Output: Libby, Arnold