The reverse search method refers to the analysis, exploration from the opposite thinking direction in the thinking process, the opposite direction, and the creation of the opposite or relative functions of things. Which of the following is the reverse search method? ['Divide one thing into several people to do it at the same time. This is the design idea of parallel computers, so that the parallel computers designed are doubled in computing speed.', 'Let several people work together for one thing. For example, safe management is to let two people control at the same time, so the "insurance" is greatly enhanced.', 'When the white refrigerator flooded the market, a well-known company launched a color refrigerator. As a result, it was welcomed by the market with its new colors, and soon entered the international market.', 'The key to the alarm is to clearly explain the location of the incident. Sometimes the delay in the alarm is due to the unknown location of the emergency. Shenzhen has sprayed alarm codes on 100,000 street lights and poles in the city to ensure that the 110 alarms can be accurately located.']