Which of the following incidents formally ended the American Civil War?
选项：

A:The actor and Confederate sympathizer John Wilkes Booth assassinated President Lincoln at Ford's Theatre in Washington.;
B:The Union received the Confederate's surrender in North Carolina.;
C:Ulysses S. Grant, the supreme command of the Union armies accepted the Confederates' surrender at Appomattox Court House. ;
D:President Lincoln used the occasion of the Union victory at Antietam to issue a preliminary Emancipation Proclamation.