In 1975, the vietnam war ended: a. leaving very few vietnamese casualties. b. leaving many americans optimistic. c. as a result of the u. s. invasion of cambodia. d. as the only war lost by the united states. e. as a military, political, and social victory for the united states.

d. As the only war lost by the United States

Explanation:

During Cold War, The war among North and South Vietnam caught the attention of the goverment of United States which ended up with entering to support South Vietnam. The goal was to restore order and stop communist influence promoted by URSS on countries like North Vietnam, however, even though the number of casualties from the North vietnamese side was higher than the USA's side, order was not set as expected. There were too many deaths, too much money spent on war, nevertherless they could not make North Vietnam surrender but USA had to retreat after signing a peace agreement between the two Vietnams. It is important to state that conflict did not completely finished when USA left, so they did not restore order and lost too much for nothing. That is why Vietnam war is considered a loss, the only war lost by the United States.

letter d is correct.

i dont know sorry, but ik that you need to pay attention in class