The earth's orbit is responcible
According to the First World War page on the Australian War Memorial website from a population of fewer than five million, 416,809 men enlisted, of which over 60,000 were killed and 156,000 wounded, gassed, or taken prisoner. The latest figure for those killed is given as 62,000.
your answer for this question is B)
Agriculture can prove extremely difficult to maintain on a rocky mountain and with such poor infrastructure it is also difficult to import goods on a JIT (Just In Time) sort of basis where you receive these goods as you need them. Infrastructure also includes communication and other services and with such a technologically developed era we depend on technology and this can deter a lot of people from settling in these regions, additionally the wildlife in these regions consists greatly of predators which can be deemed a threat to habitants who are unprepared. The sheer abundance of wildlife and non industrial landscapes can also mean that people will not want to live in these regions