Aplaintiff read of the success of a box-office hit movie about aardvarks in various entertainment journals. the movie was enormously popular among young children, and cartoon figures from the movie began appearing on t-shirts, soft drink mugs, and other novelties. the plaintiff filed suit against the studio alleging that the production company unlawfully used his ideas for the movie. the studio admitted that it had received a clay model of a cartoon animal from the plaintiff, but denied that the model had any substantial similarity to the now-famous aardvarks. the studio had returned the model to the plaintiff, but he had destroyed it. for the plaintiff to testify at trial as to the appearance of the model, which of the following is true? a the plaintiff can testify as to the appearance of the model because he has personal knowledge of it. b the plaintiff must show that the destruction of the model was not committed in bad faith. c the plaintiff must introduce a photograph of the model, if one exists. d the plaintiff must give advance notice to the opposing party that he plans to use such oral testimony in his case.