How effective were America and her allies in their attempts to defeat the Viet Cong's guerrilla tactics

Pretty horrible. First of all, the U.S did not have the proper capabilities to fight in close quarter combat. Most of the U.S technology had been invented on the basis of large scale wars. Hit and run attacks by the Vietcong cause massive casualties (and heavy economic losses) to the Americans and allies. Also, it elongated the conflict which U.S media picked on and influence popular opinion to retreat from Vietnam.

Ibelieve the answer is c