The Battle of Antietam in 1862 Was Considered a Major

The Battle of Antietam in 1862 was considered a major turning point of the Civil War because .

A) the victory afforded President Lincoln the opportunity to issue the Emancipation Proclamation
B) it was the last time Confederate troops would enter Union territory
C) General Robert E. Lee was never again as aggressive for the rest of the campaign in Virginia
D) Confederate forces were forced to hurriedly withdraw into the Carolinas