The deserts of the Middle East A.
make trade between countries impossible, so they rely heavily on foreign aid.
B.
make trade between countries impossible, so they rarely interact with each other.
C.
make trade between countries difficult, but they still trade actively.
D.
make trade between countries difficult, so they only use waterways.

How did the united states respond when north vietnam attacked a us warship and sent troops to south vietnam in the early 1960s? a.the united states declined to assist south vietnam against the north. b.us leaders authorized south vietnam to invade north vietnam. c.the president did not sign the gulf of tonkin resolution. d.congress authorized the president to escalate the conflict.