In 1965, the united states launched operation rolling thunder, which involved using aircraft to bomb north vietnam. using american ships to shell the city of hanoi. sending half a million troops to south vietnam. taking over the defense against the viet cong.

  ...Using aircraft to bomb North Vietnam.

Explanation:

  It was the name given to a bombardment campaign conducted by the United States along with South Vietnam.

  There were four major objectives to accomplish with the attacks:

  They also performed that operation as an attempt to not deploy ground forces in North Vietnam because of the restraints imposed to the U.S. in the context of the Cold War.

  I hope this answer helps you.

the answer is b: an economic crisis throughout the country.