What Factors Contributed to the Massive Increase in the European

What factors contributed to the massive increase in the European population at the turn of the twentieth century?

A) Improvements in technology that made warfare less deadly and diplomatic initiatives to prevent major conflicts
B) An increase in government projects to prevent emigration abroad and greater investment in local housing and job training
C) Improvements in public health and sanitation that extended the human life span and lowered infant mortality rates
D) The annexation of new territories and the growth of European empires, which expanded Europe far beyond its old borders