The dilemma facing Lincoln when he entered the presidency was:

A) How to maintain the authority of the federal government without provoking war with the states that had seceded
B) Whether to recognize the Confederacy as an independent, sovereign nation
C) How to work with a Congress controlled by Democrats
D) Whether to seek gradual or immediate emancipation of the slaves

Lincoln's main dilemma was how to maintain the authority of the federal government without provoking war with the states that had seceded. The southern states had already seceded and formed the Confederacy, and tensions were high between the two sides. Lincoln had to navigate this delicate situation while also working towards the reuniting of the country. The other options listed were important issues during his presidency, but the main dilemma was centered around the secession crisis.