In which of the following situations would an audit firm be considered not independent with respect to a public company audit client under the provisions of the Sarbanes-Oxley Act?

A) The client hires an audit firm member as its CFO. The CFO left the audit firm one month earlier, and participated in the most recent audit of the company.

B) The audit firm provides tax planning services to the client. The services were pre-approved by the audit committee.

C) The lead audit partner for the client has served in that capacity for the past four years.

D) The audit firm prepares the tax return for the client and this service was pre-approved by the audit committee.