General grant responded to the confederate surrender at appomattox court house by

feeding lee’s troops and sending them home.
arresting lee and sending his troops home.
arresting lee and sending his troops to prison.
executing lee and arresting his troops.

General Robert E. Lee commanded the Army of Northern Virginia. After General Gordon's failed attack on the enemy, Lee requested a meeting with Lieutenant General Ulysses S. Grant to discuss surrendering the Army of Northern Virginia and they discussed the terms.

Grant asked if Lee had anything that he wanted. Lee replied that many soldiers in his army owned their horses and wanted Grant to let the men keep their properties.

Grant understood that many of the Confederate soldiers were farmers who needed the animals for planting and in the end agreed to tell his officers to let the Confederates take their horses and mules home.  He also, told the Union supply officer to feed the Confederate army.

So there was no arresting the men, nor sending to prison and certainly there was no executions.

The answer is:

feeding Lee’s troops and sending them home.

because he had a big bear belly