Which of the Following Statements Is Correct

Which of the following statements is correct?

A) Federal Rule 605 permits a judge to testify at a trial that he or she is presiding over if he or she is a material witness to the crime.
B) According to the Code of Conduct for U.S. Judges, if a judge knows ahead of time that he or she may be a witness, he or should recuse himself or herself before the trial.
C) An attorney who fails to object to a judge's testimony during the trial is barred from raising the issue on appeal.
D) All of the above statements are correct.