Given a question and a context passage, generate the answer having the word or phrase from the context passage. Here, the answer should be a shortest continous span from the passage.

Example Input: Context: Recent genome-wide association studies (GWAS) for Caucasians identified several allelic variants associated with increased risk of developing restless legs syndrome (RLS), also known as Willis-Ekbom disease. Although the pathogenic mechanisms of RLS are not entirely understood, it is becoming increasingly evident that many diseases such as RLS can be attributed to an epistasis. The study objectives were to evaluate whether the associations of RLS with all loci determined in previous GWAS for Caucasians can be replicated significantly for the Korean population and to elucidate whether an epistasis plays a role in the pathogenesis of RLS. DNA from 320 patients with RLS and 320 age- and sex-matched controls were genotyped for variants in the RLS loci. A significant association was found for rs3923809 and rs9296249 in BTBD9 (P < 0.0001 and P = 0.001, respectively); the odds ratio (OR) for rs3923809 was 1.61 (P < 0.0001) to 1.88 (P < 0.0001) and the OR for rs9296249 was 1.44 (P = 0.001) to 1.73 (P = 0.002), according to the model of inheritance. The OR for the interaction between rs3923809 in BTBD9 and rs4626664 in PTPRD was 2.05 (P < 0.0001) in the additive model, 1.80 (P = 0.002) in the dominant model and 2.47 (P = 0.004) in the recessive model. There was no significant association between genotypes of all tested single nucleotide polymorphisms and the mean value of serum iron parameters. Our results suggest that the role of BTBD9 in the pathogenesis of restless legs syndrome is more universal across populations than previously reported and more efforts should be focused on the role of epistasis in the genetic architecture of restless legs syndrome. 
 Question: Willis-Ekbom disease is also known as?
Example Output: restless legs syndrome

Example Input: Context: Modeled after US hot website.com, group buying websites are now popular in China. These websites use the power of group buying to get competitive discounts for a daily deal on some best stuff to do, see, eat and buy in the cities across China. Discounts are available within just one click. Zhao lei, a software engineer in Beijing, loves the one-hour lunch break at noon,as it is the best time for him to check "today's special" at his favorite group buying websites . Sometimes he searches for great deals at directory sites devoted to the new shopping space. Zhao spends around 800 yuan($117.65) on group buying every month, mostly to buy food coupons for eating at some nice restaurants and occasionally to find something fun to do. " I love group buying. In addition to the competitive discounts it offers, it helps me get something fun, exciting and new, and such surprises give me a reason to try something new," he said. When he finds a really good bargain, he will send the link to friends or colleagues through MSN,QQ, or e-mail, or share the information at some social networking websites. In doing so, he often gets a certain cut off the price. At some sites, buyers are invited to leave notes about what they want to buy and the website will consider it if similar applications reach a certain number. That is how Zuo got her digital camera after waiting for two months. "It is cool. I want to buy a new digitgal camera for my trip to Switzerland this winter, but I never expected such cheap prices!" Zuo said. 
 Question: What is the passage mainly about?
Example Output: group buying

Example Input: Context: September 1939. Mrs. Kay Miniver (Greer Garson) and her family live a comfortable life at a house called 'Starlings' in Belham, a fictional village outside London, England. The house has a large garden, with a private landing stage on the River Thames at which is moored a motorboat belonging to her devoted husband Clem (Walter Pidgeon), a successful architect. They have three children: the youngsters Toby and Judy (Christopher Severn and Clare Sandars) and an older son Vin (Richard Ney) at university. They have live-in staff: Gladys the housemaid (Brenda Forbes) and Ada the cook (Marie De Becker).As World War II looms, Vin comes down from university and meets Carol Beldon (Teresa Wright), granddaughter of Lady Beldon (Dame May Whitty) from nearby Beldon Hall. Despite initial disagreements (mainly contrasting Vin's idealistic attitude to class differences with Carol's practical altruism) they fall in love. Vin proposes to Carol in front of his family at home after his younger brother prods him to give a less romantic but more honest proposal.Several months later, as the war comes closer to home with the bombing of Great Brittan, Vin feels he must "do his bit" and enlists in the Royal Air Force, qualifying as a fighter pilot. He is posted to a base near to his parents' home and is able to signal his safe return from operations to his parents by cutting his engines briefly as he flies over the house. Together with other boat owners, Clem volunteers to take his motorboat to assist in the May-June 1940 Dunkirk evacuation.Early one morning, Kay unable to sleep as Clem is still away, wanders down to the landing stage. She is startled to discover a wounded German pilot (Helmut Dantine) hiding in her garden and he holds her at gunpoint. Demanding food and a coat, the pilot maniacally asserts that the Third Reich will mercilessly overcome its enemies. She feeds him, calmly disarms him and then calls the police. Soon after, Clem returns home, exhausted, from Dunkirk.Lady Beldon visits Kay to try and convince her to talk Vin out of marrying Carol on account of her granddaughter's comparative youth. Lady Beldon is unsuccessful and admits defeat when Kay reminds her that she, too, was young when she married her late husband. Lady Beldon concedes defeat and realises that she would be foolish to try and stop the marriage. Vin and Carol are married; Carol has now also become Mrs Miniver, and they return from their honeymoon in Scotland. A key theme is that she knows he is likely to be killed in action, but the short love will fill her life. Later, Kay and her family take refuge in their Anderson shelter in the garden during an air raid, and attempt to keep their minds off the frightening bombing by reading Alice's Adventures in Wonderland, which Clem refers to as a "lovely story" as they barely survive a bomb destroys parts of the house. They take the damage with nonchalance.At the annual village flower show, Lady Beldon silently disregards the judges' decision that her rose is the winner, instead announcing the entry of the local stationmaster, Mr. Ballard (Henry Travers), named the "Mrs. Miniver" rose, as the winner, with her own rose taking second prize. As air raid sirens sound and the villagers take refuge in the cellars of Beldon Hall, Kay and Carol drive Vin to join his squadron. On their journey home they witness fighter planes in a 'dogfight'. For safety, Kay stops the car and they see the German plane crash. Kay realises Carol has been wounded by shots from the plane and takes her back to 'Starlings'. She dies a few minutes after they reach home. Kay is devastated. When Vin returns from battle, he already knows the terrible news. Unexpectedly he is the survivor, and she the one who gives her life for England.The villagers assemble at the badly damaged church where their vicar (Henry Wilcoxon) affirms their determination in a powerful sermon:"We in this quiet corner of England have suffered the loss of friends very dear to us, some 
 Question: Who meets Carol?
Example Output:
vin