Can the Defense Impeach Becky If She Testifies at Trial

Can the defense impeach Becky if she testifies at trial

A) No, only expert witnesses can be impeached.
B) No, only individuals who are not telling the truth can be impeached at trial.
C) No, the defense can try to show that Becky is not competent to be a witness at a voir dire hearing, but if the judge roles she is a competent witness she cannot be impeached.
D) Yes, the defense is entitled to try to impeach all prosecution witnesses.