Which of the following is NOT a rule of testimony?

Providing personal opinions is not considered a rule of testimony because testimony is expected to be based on facts and personal experiences rather than subjective interpretations. The integrity of the testimony relies on the speaker accurately recounting what they have witnessed or experienced without injecting their personal biases or feelings.

In contrast, the other aspects emphasized are integral to ensuring the reliability and clarity of the testimony. Telling the truth establishes the foundation of credibility, while avoiding joking and wisecracks maintains a serious demeanor suitable for court proceedings or formal inquiries. Answering audibly is essential for ensuring that the testimony is heard and understood effectively. Collectively, these rules help uphold the professionalism and integrity of the testimonial process, which is critical in legal or investigative contexts.