Q. A CPA must sign the preparer's declaration on a federal income tax return

a. only when the CPA prepares a tax return for compensation

b. only when the CPA can declare that a tax is based on incormation of which the CPA has personal knowledge.

The answer is "a", but I think it should be "b" since becker stated that "the tax preparer's declaration on the tax return indicates that the information contained on the return is true, correct, and complete to the best of the tax preparer's knowledge and belief."

Could anybody help me to explain it?

Thanks.