The chemical name is polytetrafluoroethylene and the commercial name is Teflon. It is widely used in the inner pot of rice cookers. Studies have shown that the substance will become toxic under high temperature above 260 degrees, so some people think that rice cookers will make " Poison Rice ". Which of the following, if true, would best challenge the above view? ['Teflon as a coating is particularly easy to peel off and mix into food.', 'The working temperature of the Teflon inner rice cooker is 119 degrees.', 'Teflon is toxic enough to cause cancer under high temperature conditions.', 'Teflon materials are also used in medical, metallurgical and other fields.']