An expert from the Ministry of Public Security said that the psychological pressure of lying can cause certain physiological changes. With the aid of a polygraph, the physical surface of a liar can be measured, thereby making the polygraph result reliable. Which of the following statements, if true, would most effectively weaken the argument? ? ['Polygraph is an instrument that requires frequent maintenance and is prone to failure.', 'For some people, lying can only lead to less psychological stress.', 'All kinds of psychological stress can cause similar psychological stress.', 'Measuring instruments like polygraphs can also be misused and abused.']