Prior to the London Olympics, in order to effectively improve air quality in London, the mayor of London and member of the Olympic Committee, Boris Johnson, announced that large trucks and light buses must meet low-emission zone standards by January 2012. It was originally included in low-emission zones since October 2010. If it does not meet the emission standards, a fine must be paid. This shows that the biggest cause of pollution in London is the amount of pollution emitted by traffic. Which of the following, if true, best supports the above judgment? ['The biggest pollution problem in London is air pollution, and the pollutants in the air mainly come from the emissions of traffic flow.', 'Since the turn of the 2000s, London has not seen any innovation or progress in limiting vehicle emissions, and urban air quality has also been poor.', 'The generation of pollutants comes from the direct discharge of pollution on the one hand, and from the weather on the other, because we cannot control the weather, we can only control the amount of pollution emitted.', 'The huge amount of traffic is the main reason for the two major pollution sources (particulate matter and nitrogen dioxide) in the city. A diesel car produces much more pollution than a gasoline car, and London and many vehicles are powered by diesel.']