Task: Question Answering
Input (English): Background Paragraph: In the U.S., the majority of electricity is produced by burning coal or other fossil fuels. This causes air pollution, acid rain, and global warming. Fossil fuels are also limited and may eventually run out. Like fossil fuels, radioactive elements are limited. In fact, they are relatively rare, so they could run out sooner rather than later. On the other hand, nuclear fission does not release air pollution or cause the other environmental problems associated with burning fossil fuels. This is the major advantage of using nuclear fission as a source of energy. 
Story: Two sister cities used different methods to produce electricity. London used fossil fuels, while Edmonton use entirely hydro power to generate energy. 
Question: Which city causes more acid rain?
Output (English): London.