The correct options are
B Water pipes and electric lines can be fitted underground.
C Walls may be built around the slopes of hills prone to landslides.
There are a number of precautions to be taken in case of landslides. Two such precautions are ensuring that electric lines and water pipes are fitted underground to protect them from damage during a landslide, and building tall walls around the slopes of landslide-prone hills in order to block rocks and soil from sliding onto roads and into houses.