Ans: C. Common witness"Except common witness all other options are expe witnesses".Only the common witness can be considered as having first-hand knowledge in the cou of law.In the cou procedures, this phrase refers to the personal understanding of circumstances and events, which is re-told and explained by a witness in a couroom, during a cou hearing on the concrete lawsuit.In other words, the witness has been an eye-witness of these circumstances or events and so has accepted directly. Therefore they have clear and detailed personal knowledge of it. An example is a statement in affidavits.