Based on what Lincoln says, it can be inferred that:

a. He opposes slavery and supports full political equality for African-Americans, but opposes social integration

b. He supports slavery in the South, but nowhere else, and full political equality for African-Americans in the Northern states

c. He opposes slavery, but would not extend any additional measures for political or social equality to African-Americans

d. He opposes slavery and supports social and political equality for African-Americans