Which event forced chinese communists and nationalists to join forces
A. The battle against Chinese warlords
B. The invasion by Japan in 1937
C. The end of the war against Japan in 1945
D. The invasion by Manchuria in 1937

Generally, around the globe there are 105 boys born for every 100 girls. however, recently in some countries, this ratio has been altered with a much larger proportion of boys being born in some countries. the primary reason for this shift to a higher proportion of male births has been