The best answer is, D. It limited it by saying that opposition to the draft was a danger to the country during wartime.
The Supreme Court Ruling in Schenck vs. United States saw a limitation of the rights associated with free speech when these instances interfere with wartime military recruitment. The ruling found that Schenck was not protected by the First Amendment when distributing flyers which encouraged young men to avoid enlisting in the draft because this created an atmosphere of danger for the United States.
