This task is about writing a correct answer for the reading comprehension task. Based on the information provided in a given passage, you should identify the shortest continuous text span from the passage that serves as an answer to the given question. Avoid answers that are incorrect or provides incomplete justification for the question.

[EX Q]: Passage: The "snug", sometimes called the smoke room, was typically a small, very private room with access to the bar that had a frosted glass external window, set above head height. A higher price was paid for beer in the snug and nobody could look in and see the drinkers. It was not only the wealthy visitors who would use these rooms. The snug was for patrons who preferred not to be seen in the public bar. Ladies would often enjoy a private drink in the snug in a time when it was frowned upon for women to be in a pub. The local police officer might nip in for a quiet pint, the parish priest for his evening whisky, or lovers for a rendezvous. Question: What was the relationship between the price of beer in the smoke room versus the rest of the bar?
[EX A]: higher

[EX Q]: Passage: Since 2002, the North East of the country has seen sectarian violence by Boko Haram, an Islamist movement that seeks to abolish the secular system of government and establish Sharia law. Nigerian President Goodluck Jonathan in May 2014 claimed that Boko Haram attacks have left at least 12,000 people dead and 8,000 people crippled. At the same time, neighbouring countries, Benin, Chad, Cameroon and Niger joined Nigeria in a united effort to combat Boko Haram in the aftermath of a world media highlighted kidnapping of 276 schoolgirls and the spread of Boko Haram attacks to these countries. Question: Who is the President of Nigeria?
[EX A]: Goodluck Jonathan

[EX Q]: Passage: The London Underground in England is one of the few networks that uses a four-rail system. The additional rail carries the electrical return that, on third rail and overhead networks, is provided by the running rails. On the London Underground, a top-contact third rail is beside the track, energized at +420v DC, and a top-contact fourth rail is located centrally between the running rails at 210v DC, which combine to provide a traction voltage of 630v DC. London Underground is now upgrading its fourth rail system to 750v DC with a positive conductor rail energised to +500v DC and a negative conductor rail energised to -250v DC. However, many older sections in tunnels are still energised to 630v DC. The same system was used for Milan's earliest underground line, Milan Metro's line 1, whose more recent lines use an overhead catenary or a third rail. Question: What is the voltage of the return rail?
[EX A]:
210v DC