The correct options are
A Constructing and maintaining railways and roadways is difficult because it requires a lot of planning.
B More manpower is required to lay roads and railway tracks.
C Waterways are easier because oceans, rivers and seas are natural mediums.
D Ships can carry huge loads of goods in a single journey.
A ship is so huge that it can transport a large number of goods at a time. Hence, water transport is the easiest and cheapest mode of transport. Constructing and maintaining railways and roadways is difficult because it requires a lot of planning and manpower to lay roads and railway tracks. Waterways are easier that way because oceans, rivers and seas are natural mediums.