Read this summary of the Klopfer v. North Carolina Supreme Court case.

The state of North Carolina charged Peter Klopfer with trespass for participating in a civil rights protest at a restaurant. The jury could not agree on a verdict, which meant another trial would be held. Rather than retry Klopfer immediately, the prosecutor used a legal tactic that allowed him to keep the charge open, but put off another trial indefinitely. This meant that Klopfer would have an unresolved criminal charge hanging over his head. Klopfer objected, and the case made its way to the Supreme Court. The Supreme Court ruled in Klopfer’s favor on Sixth Amendment grounds.

Which part of the Sixth Amendment applied to this case?

a defendant’s right to a lawyer
a defendant’s right to an unbiased jury
a defendant’s right to witness testimony
a defendant’s right to a quick and public trial