Which of the following terms describes a statement made by someone who has firsthand knowledge of an event?

The term that accurately describes a statement made by someone who has firsthand knowledge of an event is "Direct Testimony." This refers specifically to the accounts given by witnesses who directly experienced or observed an event. Such testimony is valuable in legal and formal contexts, as it provides a direct link to the facts of the case without filtering through the perspectives or interpretations of others.

In contrast, expert testimony typically involves opinions or insights from individuals with specialized knowledge relevant to the case, rather than firsthand observations. Circumstantial evidence refers to indirect evidence that implies a fact but does not establish it definitively, depending on inference rather than direct observation. Validation is more generally related to confirming the accuracy or reliability of information and doesn’t specifically pertain to firsthand accounts.