Which of the following is not a preparer penalty?

a.Tax preparers may be assessed a penalty for endorsing or cashing a refund check issued to a taxpayer.

b.Tax preparers may be assessed a penalty for failing to give the taxpayer the preparer's workpapers.

c.Tax preparers may be assessed a penalty for failing to sign a tax return.

d.Tax preparers may be assessed a penalty for failing to keep a copy of the prepared return.