For each of the following situations, indicate the amount of the penalty that could be imposed on the tax return preparer:
a. A tax return preparer understates the taxpayer’s tax liability with a frivolous position and does not disclose the position. $ _________________
b. A tax return preparer fails to furnish his identifying number. $ _________________
c. A tax return preparer aids a taxpayer in understating a tax liability. $ ______________
d. A tax return preparer endorses and cashes a client’s tax refund check. $ ____________