There Is a General Rule That the Party Who Calls

There is a general rule that the party who calls a witness cannot seek to cross-examine the witness or seek to discredit the witness even if he has failed to give the evidence expected ('has not come up to proof') and even though the expected evidence is contained in his witness statement. In these circumstances, which of the statements below represents an incorrect course of action?

A) If the witness during his evidence is showing that he will not 'come up to proof' and give the evidence expected of him the party may withdraw the witness from his case.
B) The party calling that witness may call other witnesses to give evidence that was expected of the witness who did not come up to proof.
C) If the witness who has not come up to proof does not otherwise seem in any way hostile to the party calling him, he is only an unfavourable witness and the party who has called him has no rights to cross-examine him or otherwise seek to discredit him
D) If the witness appears to the judge to be a witness who is hostile to the party who has called him or seems intent not to tell the truth then that witness can be deemed a 'hostile witness' and, at the judge's discretion, the party who has called him may be permitted to cross-examine him.