Towns often developed near oases because it was easy access to water and they could farm there.
Cold weather is the best answer!
a) - Poland was also at war with the Soviet, unlikely it would help
b) Soviet Union has only very limited access to the Mediterranean, which likely was completly cut off at the time anyway
c) they could have it, but China was too busy fighting its own war!
The answer is c. Civil War. The states of the South were
against any interference from the Federal government particularly on the issue
of slavery. When Lincoln was elected,
the Southern states felt that their rights to own slaves would be jeopardized and
this would lead to Civil War.