The correct answer is B) From the sweat of other men's faces.
In this passage, Lincoln is referring to how Northerners and Southerners have both been able to make money/food off the work of slaves. Lincoln made this connection during the Civil War era, as to show the consequences of the United States actions over the course of the last two centuries of slavery. This line represents how the hard labor of others allowed for individuals to reap the benefits.