Answer:
c. American bombing raids in North Vietnam
Step-by-step explanation:
Operation Rolling Thunder was a code name for the campaign under which the U.S. army was about to throw bombs over the Democratic Republic Of Vietnam, in other words, North Vietnam during the Vietnam War. At first, the campaign was planned to last 8 weeks but in the end it took almost 4 years, with over 600,00 tons of explosives having been dropped on Vietnamese territory by the United States army.