Under what condition can an accomplice's confession be admitted in court?

The correct answer is based on the principle of hearsay and the rights of the accused under the Sixth Amendment. A defendant's confession can be introduced as evidence in court when they take the stand and are subject to cross-examination. This ensures that the confession can be tested for its credibility and accuracy, allowing the opposing party to challenge its validity and the context in which it was made.

This scenario follows the legal foundation that for any confession or admission by a party, it must be made under circumstances where the other party has the opportunity to scrutinize it. Cross-examination serves as a critical tool in the courtroom, allowing the jury to assess the reliability of the statement being presented.

Other options do not provide the necessary conditions under which an accomplice's confession could be admissible. For instance, a confession does not require signatures from all parties involved, nor does it hinge on whether the confessing defendant does or does not take the stand. Additionally, a statement referring to co-defendants alone does not provide the appropriate procedural safeguards required for the admission of such confessions in court. Therefore, the requirement for cross-examination of the confessing defendant stands as the crucial element that renders their confession admissible.