When the traffic lights turn red, we will stop driving a car or crossing a street. Why is red used for traffic lights instead of other colors? As we know, scattering   happens when light goes through the air. For the same media  , if the _ is long, the sscattering will be short. If the wavelength is short, then the scattering will be long. Of all lights we can see, red has the longest wavelength. So the scattering is the weakest. That means the red light travels far. In fact, it travels farther on rainy days. Using the red light can help drivers in farther places see the lights. It helps drivers slow down or stop in time. So there will be fewer accidents. Moreover, red can also excite people. We can act more quickly when we see the color red. In a word, red lights help drivers stop in time and help prevent accidents. According to the passage, the scattering of the red light is the   _  .
longest weakest farthest brightest