The government tried to stop the new york times from publishing classified material by using a concept known as
a. the espionage act.
b. prior restraint.
c. symbolic speech.
d. clear and present danger.

The correct answer is:  

B. prior restraint.  

In 1971 the US government solicited a restraining order that prevented the Times from posting any further articles based in the Pentagon Papers. The claim was prior restraint, which means the Government can show sufficient evidence that the publication would cause a "grave and irreparable" danger.

Later on, the New York Times Co. v. United States (1971) ruling made it possible for The New York Times and The Washington Post newspapers to publish without risk of government censorship or punishment.

so what is your question?