Many consumers in a certain place complained that the quality of the air conditioner of a certain brand is not good, and the cooling effect is poor. In response, the chief engineer of the brand air conditioner responded that the reason why the air conditioner did not operate properly was that the local air quality was too poor. If the following options are true, which of the following is the most effective way to refute the engineer's point of view? ["The brand's air conditioners work very well in areas with good air quality.", 'The brand air conditioner has not experienced a large number of quality complaints in other regions.', 'Not all air conditioners are affected by air quality.', 'All air conditioners should be guaranteed to function properly in the local area before they can be sold.']