While working on a construction project, a plaintiff was injured when a heavy object struck his knee. although the plaintiff was fully compensated for his injuries at the time of the incident, he now seeks disability payments from the construction company because he has developed arthritis in the same knee. the construction company claims that the arthritis has nothing to do with the plaintiff's on-the-job injury and refuses to pay him disability money. the plaintiff sues. a doctor takes the stand to testify for the plaintiff. he is qualified as an expert witness and during direct examination states that in his opinion the blow to the plaintiff's knee caused his arthritis. on cross-examination, the construction company's attorney produces a treatise on arthritis and asks the doctor if the treatise is considered to be authoritative. the doctor responds that the treatise is a standard authority in the field, but that he did not rely on it in forming his professional opinion regarding the plaintiff's condition. the attorney then seeks to introduce into evidence a statement in the treatise that "the idea that arthritis can be caused by a single traumatic event is purely folklore, although it is widely believed by the ignorant who have no scientific basis for their beliefs." the plaintiff's attorney objects. how should the court rule on the admissibility of the statement from the treatise? a admissible, but only for the purpose of impeaching the doctor's testimony. b admissible, but only as substantive evidence. c admissible, both as substantive evidence and for purposes of impeaching the doctor. d inadmissible.