Which of the following acts by a CPA would be most likely to be considered an act discreditable to the profession under the AICPA Code of Professional Conduct?

1. Allowing a client's new CPA firm to review the prior year audit working papers after the client has requested the CPA to do so.
2. Performing a review of a client that normally requests an audit.
3. Refusing to return client records until the audit fee is paid.
4. Signing a tax return as the preparer.