One of the main transportation challenges for people living in extremely cold climates is a. railway tracks that constantly crack and break due to ice b. waterways that are frozen over half the year c. the high cost of travel during the winter months d. the inability to use anything except dogsleds in the winter months

The correct answer is - B. waterways that are frozen over half the year.

The people that live in areas that have extremely cold climates face numerous problems because of the very low temperatures, long-lasting ice and snow. One of the big problems is the traveling. The waterways are an effective way of transport in this areas, being without obstacles, going over large distances, relatively cheap. The problem is that for over half a year, this main transportation mean is not usable because it is frozen. While that makes it easier to get from one side of the river to another by simply walking over the ice, the people are not able to use the water for travel, thus they have to go to slower, more dangerous ways to travel.