What Was the Significance of Townsend V

What was the significance of Townsend v. Burke (1948) in relation to the Sixth Amendment?

A) The deliberate use of perjured testimony violates due process laws.
B) Police may not question the accused without the attorney present.
C) A convicted offender has a right to counsel at the time of sentencing.
D) Even when statements regarding the charged offense are not admissible because the person's Sixth Amendment rights were violated, they are still admissible to impeach the witness.