The correct answer is C) Lee's retreat from Petersburg.
The event that led to the fall of the Confederate capital, Richmond, Virginia was Lee's retreat from Petersburg.
The Battle of Petersburg was fought on June 15, 1864. The troops of the Union, led by General Ulysses S. Grant attacked the Confederate Army led by Robert E. Lee, 23 miles south the capital city of Virginia: Richmond. Robert Lee surrendered on April 2, 1865, and retire to Appomattox, Virginia, where he finally surrendered to end the Civil War on April 9, 1865.