What was Lincoln's constitution justification for issuing the Emancipation Proclamation?
A. Under the Commerce Clause, the government had the power to regulate slavery
B. Under the Necessary and Proper Clause, Lincoln could do anything he wanted
C. Because slaves were not allowed to speak their minds, slavery violated the First Amendment guarantee of freedom of speech
D. As commander-in-chef, Lincoln had the power and responsibility to take measures that were military necessities in the struggle to preserve the Union