Relevant Evidence in a Suit for Specific Performance

So, I'm having a fight with my friend Rohan over this Evidence Act question. Our professor, Sir, asked us to answer this on the last exam. I said yes, I'm right, but Rohan thinks I'm wrong. I told him we can ask the community here to settle it.

Here's the question: "X, a witness, is examined in chief by A, plaintiff's lawyer. In cross-examination by B, defendant's lawyer, X says, "I have no knowledge of any prior dealings between A and B". B then asks X, "Have you not made a statement, in writing, to A, prior to this lawsuit, stating that he had no prior dealings with B?" X says, "No, it was a draft and not final.