A CPA who prepares clients' federal income tax returns for a fee must A. Keep a completed copy of each return for a specified period of time or keep a summarized list of specified return information. B. Indicate the CPA's federal identification number on a tax return only if the return reflects tax due from the taxpayer. C. Receive client documentation supporting all travel and entertainment expenses deducted on the return. D. File certain required notices and powers of attorney with the IRS before preparing any returns.