Answer:
<em><u>d.) Schenck v. U.S.</u></em>
Explanation:
Schenck v U.S. was a Supreme Course case from 1919. I believe it basically referred to the Espionage Act as an example that free speech is a right under the 1st Amendment.
An example of a command economy was the Soviet Union during the Cod War, when it had Communism as the economical system.
In Communist economies, or in command economies generally the planning is done by the government - we call it central planning (answer B)