When a galloping car needs to be braked immediately, the response time of a few milliseconds is very critical. Sometimes, the distance of a few meters determines the life and death of people. Recently, researchers have used simulation driving systems, eye-tracking technology and other methods Five groups of subjects were faced with differently-moving traffic signs, and then tested how fast they responded. It was found that the more dynamic traffic signs did allow the subjects to respond faster. Therefore, they suggested relevant departments, The original traffic warning signs should be replaced with more dynamic signs in order to improve the driver's response speed. Which of the following, if true, best indicates that the above-mentioned researcher's suggestions are difficult to achieve the desired goal? ['Replacing the original traffic warning sign is a huge and tedious project, which requires a huge investment.', 'Of the five groups of researchers selected by the researcher, some were not driving long enough, and some did not even drive.', 'When the driver understands the actual meaning of a strong dynamic traffic warning sign, his reaction speed will drop to the previous level.', 'If the people on the screen seem to be running, it is easy to reminisce the picture of a pedestrian rushing past your car.']