Questions 18 to 20 are based on the following passage. At the end of the passage, you will be given 15 seconds to answer the questions. Now listen to the passage. According to the professor, what did private companies do after they built new roads
A．Reduced charges for transporting farm products. B．Required payment from vehicles that used their roads. C．Made repairs to older roads. D．Installed streetlights on roads connecting major cities.