During which phase is a witness first required to take an oath?

The correct response identifies the phase known as "Swearing in," which is when a witness is first required to take an oath before giving testimony in court. This process is essential because it serves to affirm that the witness understands the importance of telling the truth. The act of swearing in is a formal procedure that typically occurs before any questioning, ensuring that the integrity of the testimony is secured from the outset.

This foundational step is critical in legal proceedings, as witnesses need to be bound by their oath to provide truthful and factual information; this is essential for the fair administration of justice. Taking an oath is a legal requirement, and it establishes the framework within which the witness's subsequent statements and testimony can be evaluated and trusted.

The other options refer to stages of the process where the witness is already providing testimony, but at these points, they have typically already taken their oath, making "Swearing in" the correct and crucial initial phase in which the oath is administered.