Answer:
superior firepower ( D )
Explanation:
during the Vietnam War, US troops had a superior firepower when compared to the firepower of the Vietnamese troops and that was a very big advantage because having a superior Firepower meant that you could sustain a battle as long as necessary. what they lacked in the Geographic knowledge of the the region that the Vietnamese troops had,was compensated for by having a superior Firepower.
This was the major advantage the US troops had over the Vietnamese troops
