A researcher wants to know whether people in his community like Coca-Cola or Pepsi. He found someone who likes Coca-Cola and asked them to indicate their preferences by tasting in a glass of Coca-Cola and a glass of Pepsi. There is no label on the cup to avoid trademark Triggered a clear prejudice, so marked "1" on Pepsi, and marked "2" on Coca-Cola cups. The results show that more than half of the people prefer Pepsi-Cola over Coca-Cola. Which of the following, if true, is most likely to weaken the conclusions of the above argument? ['Participants received certain hints and felt that their answers would be taken seriously.', 'Many of the participants in the experiment have never drank both colas at the same time, and even 30% of the participants have only drank one of the colas.', 'Most participants are aware of the market share of Coca-Cola and Pepsi, and research shows that they generally have a sympathy for the weak.', 'In another controlled experiment with participants, an interesting result was found: most of these experimenters prefer the number l over the number 2.']