Which essential element identifies the individuals involved in an event in a well-written report?

In a well-written report, identifying the individuals involved in an event is crucial for clarity and context. The element that directly addresses this need is the "who" component. It specifies the people relevant to the situation being reported, such as witnesses, victims, or suspects. By clearly stating who was involved, the report provides the necessary information to understand the dynamics of the event and the responsibilities of each party.

The other options serve different but important purposes in a report. For example, "what" describes the nature of the event, "when" specifies the timing, and "how" explains the manner or method in which something occurred. While these elements are vital to provide a full picture, it is the "who" that directly answers the question of individuals' involvement, making it the key element needed for proper identification in the report.