At 180 degrees longitude, the represents the point at which the eastern and western hemispheres experience different days.
a. equator
b. prime meridian
c. tropic of cancer
d. international date line

The area where the Eastern and Western Hemispheres meet but experience different days is known as the d. International Date Line 

It's actually not a straight line since it accommodates the land - so it goes around some places as not to split the date on land.

Had a democratic form of government

It's either  a. chiang kai-shek and the nationalists turned against the communists and killed hundreds of them. orb. hundreds of peasants were killed in shanghai during the period of warlord rule.  if we take into account that there was warlord rule at the time, i think that it's b (not entirely sure though)just my best thoughts.