The correct answer is C. Increased population growth. This enabled the people to have many workers in their factories and it also enabled the England to have a large army that would go and colonize and take the resources back to England. The other things weren't that helpful.
They all used the same routes to travel the ocean
Typically they will all earn same amount of income (money) no matter what job they are working in. Communism also usually has 1 leader or ruler.
The Vietnamese suffered Great Depression in the 1930s. This led to fall in the prices of rubber and rice, rise in rural debts, unemployment and rural uprisings. Since the provinces of Nghe An and Ha Tinh got the roughest end of this deal and had an old radical tradition, whenever the colonial system came under pressure, these regions were the first to rise up in rebellion. Hence, they were referred to 'electrical fuses' of Vietnam.
