Which of the Following Is false with Respect to the Jet

Multiple Choice

Which of the following is false with respect to the jet streams?

A) these upper-level westerly wind flows have a tube-like shape,with the highest velocities occurring toward the center of the "tube."
B) they require airlines to allot more time for flights traveling from east to west,and less time for flights from west to east.
C) they occur above the subtropics and the polar front.
D) they flow from east to west.
E) there are two jet streams that exist over North America.