Final answer:
Charles's case, which concerns a potential violation of his First Amendment right to free speech under the Espionage Act of 1917, would be tried in B)the Supreme Court of the United States because it involves constitutional law.
Step-by-step explanation:
In the case of Charles, who believes that the Espionage Act of 1917, a federal law that outlawed actions interfering with military operations, violated his right to free speech, the appropriate court for trial would be a federal court. This is because the issue at hand involves constitutional law, specifically a potential violation of the First Amendment of the U.S. Constitution which guarantees freedom of speech. Cases that invoke the U.S. Constitution or federal law are within the jurisdiction of the federal courts. According to the U.S. judicial system structure, after the indictment by a grand jury, if necessary, the case would proceed to a trial in a federal court where a judge and jury would be present. The judge oversees the trial's proceedings while the jury is responsible for determining the innocence or guilt of the defendant.
Therefore, the correct answer to where Charles's case would be tried is: B. the Supreme Court of the United States because it involved constitutional law.