According to Oakes, how did Lincoln react to Democrats who accused him of miscegenation for inviting Douglass to the White House

a) Lincoln publicly denied that Douglass had visited the White House.

b) Lincoln reacted by inviting Douglass to the White House a second time.

c) Lincoln forced Douglass into exile to prove the public he supported colonization.

d) Lincoln recalled the proclamation emancipation of southern black to appease his critics.