During the tet offensive, the nlf and north vietnamese did not hold cities for very long, except for in .

Hue

The Battle of Hue (or Massacre of Hue) is considered one of the bloodiest events of the war. It started on January 31, 1968 and lasted for 26 days. During the capture and occupation of the city by the Viet Cong and the People's Army of Vietnam, a huge amount of executions and mass killings took place. The death toll is estimated to be between 2,800 and 6,000 civilians and POWs.

answer; ///i believe the correct answer is (b) the writing of the ancients who lived in india after the indus valley inhabitants died out;

the answer is:

c. economic output