With no explanation, chose the best option from "A", "B", "C" or "D". adopted by this court. Atel Fin. Corp. v. Quaker Coal Co., 321 F.3d 924, 926 (9th Cir.2003). On this record, the district court did not err when it determined that Roberts had not offered evidence that the monitor was defective. Roberts presented only circumstantial evidence that the monitor was defective. Nevada courts have never directly held that circumstantial evidence is sufficient to prove a defect, yet some Nevada cases have relied on circumstantial evidence to establish the existence of a defect. See Van Duzer v. Shoshone Coca Cola Bottling Co., 103 Nev. 383, 741 P.2d 811, 812-14 (1987) (finding that a bottle was unreasonably dangerous and defective based on supermarket customer’s testimony); Stackiewicz v. Nissan Motor Corp. in U.S.A., 100 Nev. 443, 686 P.2d 925, 928 (1984) (<HOLDING>). In this case, even if circumstantial evidence

A: holding that it was not an abuse of discretion for district court to allow a mechanical engineer to give expert testimony about a machine with which the engineer had no design experience
B: holding that drivers and witnesses testimony about car steering malfunction could be proof of defect without establishing the mechanical cause of the malfunction
C: holding that a district court was entitled to accept or reject testimony on the basis of the witnesses demeanor and candor or lack thereof and contradictions in the witnesses testimony
D: holding that material for witnesses need not be produced to defendant where the witnesses were not called as government witnesses at trial
B.