What event ultimately ended the civil war?

The proper answer is B. Entrapment of conferedate soldiers at Appomattox Courhouse

Why?

After 10 months of starvation and desertions, General Robert E. Lee decided to abandon the cities and regroup in North Carolina with the general Joseph E. Johnston. After his failure in the battle of Forth Stedman on March 25, 1865. he decided to get provisions on Amelia Court House. However, he noticed there was nothing there (rations and supplies) and decided to wait for 5 days there to leverage rations on his army.

Grant’s army was going parallel to his movements, towards Appomattox River. Lee decided to change his strategy and go west with haste toward Farmville, Virginia, where he would get rations from the South Side Railroad. Trying to cross the river, Lee's army was cut off with more than 8,000 deceases.

Lee moved north to Cumberland Church before retreating to the west. there he received a letter from Grant demanding his surrender. Despite all the facts that have been affecting him and his troops, Lee refused Grant’s commands.

When he stopped by Appomattox Courthouse to get supplies, he was surprised by Union cavalry coming from the south. there was no comparison to Grant’s force of  63,000 troops. Once Lee notices there was no other good option than surrender, he accepted the deal.

Documents were signed at the parlor of the Wilmer McLean's home at one o’clock that afternoon.

d is the best answer for this question.