The wave structure of the polar front and associated upper-tropospheric jet stream is caused by a. surface temperature contrasts between oceans and continents.
b. large-scale mountain ranges.
c. transient weather disturbances (mid-latitude low pressure systems).
d. (all of the above)

Master planned communities outside of chicago. note: population density means people living in an area per square mile. chicago, an urban and highly populated area has a much more higher density than a desert, amish community, settlement, or nomadic region.

The correct option to this statement would be true

Dwould be tehr correct answer

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.