With no explanation, chose the best option from "A", "B", "C" or "D". extrinsic corroborating evidence of the victim’s acts of violence is admissible to show defendant’s . state of mind, we now hold the lesser-that a defendant claiming self defense may show his own state of mind by testifying that he knew of the victim’s prior acts of violence. Therefore, the district court erred when it held that Saenz could not, as a matter of law, show his state of mind at the time of his attack by testifying that he knew about the victim’s past acts. Moreover, the error was not harmless. By excluding the evidence, the district court prevented Saenz from supporting his claim of self-defense. Error cannot be harmless where it prevents the defendant from providing an evidentiary basis for his defense. Cf. United States v. Thomas, 134 F.3d 975, 980 (9th Cir.1998) (<HOLDING>). Accordingly, Saenz’s conviction is reversed.

A: holding that erroneous exclusion of evidence regarding defendants lack of criminal record was not harmless in prosecution for drug offenses in which defendant asserted entrapment
B: holding that the trial courts erroneous admission of an experts opinion that the defendant was guilty was harmless where the prosecution produced overwhelming evidence of guilt
C: holding that the plaintiff must show that there was a lack of probable cause for the criminal prosecution
D: holding exclusion was harmless error
A.