The main driving force of the Earths ocean currents is

The main driving force of the Earths ocean
  currents is
 
  a. the tilt of the Earth on its axis.
  b. differences in the ocean depths.
  c. differences in temperature at different parts
  of the ocean..
  d. relative amount of landmasses versus
  amount of ocean.
  e. the prevailing winds.

Question 2

A rain shadow forms on the west side of the
  Allegheny Mountains. What for certain can be
  said about conditions on the west side of the
  Allegheny Mountains?
 
  a. there is more rain than on the east side
  b. there is less rain than on the east side
  c. there are higher temperatures than on the
  east side
  d. there are lower temperatures on the west
  side
  e. there is a combination of rain effect and
  temperature effect on the east side
  compared to the west side