The Government in a Criminal Case May

The government in a criminal case may:

A) never impeach its own witness.
B) impeach its own witness if it can be demonstrated that it has been entrapped by previous contradictory statements.
C) impeach its own witness if the witness refuses to give testimony the government anticipated.
D) not ask its own witness questions that would indicate the witness had been previously convicted of a crime because this is the function of the defense counsel.