The correct answer is: Only I and II follow.
The statement says that there have been quite a few incidents of highway robbery on the super expressway between cities A and B during recent months. This means that there is a high risk of robbery on the expressway.
Course of action I is to set up police checkpoints along the expressway. This will help to deter robbers and catch them if they do attempt to rob someone.
Course of action II is to close down the expressway until the robbers are apprehended. This will stop people from being robbed, but it will also inconvenience a lot of people who use the expressway.
Course of action III is to give people training on how to tackle robbers. This may help people to defend themselves if they are robbed, but it is not a surefire way to prevent robbery.
Therefore, only course of action I and II are likely to be effective in preventing highway robbery on the super expressway between cities A and B.