Industrial scientists have hypothesized that much of the nitrous oxide that contributes to air pollution originates from the burning of organic matter in forest fires. The results of one extensive study in which smoke samples taken from forest fires were bottled and then analyzed in a research laboratory supports this hypothesis, since the analysis showed that all of the samples contained high concentrations of nitrous oxide. Which one of the following, if true, most undermines the argument? ['The production of synthetic products such as nylon is responsible for up to 10 percent of the nitrous oxide present in the atmosphere.', 'Soil bacteria that feed on ammonium compounds present in organic ash are thought by some scientists to excrete small amounts of nitrous oxide that then enter the atmosphere.', 'By using gas-analyzing devices mounted on helicopters, researchers can perform on-site analyses of smoke instead of sending smoke samples to laboratories for analysis.', 'When in a closed container, the gases in smoke produced by forest fires quickly react with each other thereby producing high concentrations of nitrous oxide.']