During the Persian Gulf War, Six Anti-War Demonstrators Climbed Up

During the Persian Gulf War, six anti-war demonstrators climbed up the fire escape and onto the roof of an Armed Services Recruiting Station building where they lowered the flag flying over the building and burned it. Their reason for doing this was to protest the government's involvement in the Persian Gulf War. They were indicted and convicted for criminal trespass and malicious destruction of government property. On appeal, they contended that their conviction violated their rights under the First Amendment. The appeals court should:

A) set the conviction aside on the grounds that flag burning is constitutionally protected symbolic speech.
B) set the conviction aside on the ground that the chosen location of the demonstration is a public forum.
C) affirm the conviction under the O'Brien test because the government has a substantial nonspeech interest in regulating trespassing on the roof of government buildings and destroying government property.
D) affirm the conviction under the clear and present danger doctrine.