The recent instability in Southeast Asia is due to the effects of bird flu. However, if there is no turbulence in the economic situation, the impact of bird flu on the situation will not be obvious. Therefore, to prevent the situation from being unstable, the economic situation must be stabilized. Which of the following, if true, would most weaken the conclusion? ['Turmoil in the economic situation has nothing to do with bird flu.', 'Prior to bird flu, the situation in Southeast Asia was already unstable.', 'Southeast Asia has not tried to prevent bird flu.', 'Before the economic turmoil, outbreaks like bird flu have caused instability in Southeast Asia many times.']