Choice "A" is correct. A tax preparer must make reasonable inquiries if the taxpayer's information is incomplete.Rule: A compensated preparer is liable for a penalty if his understatement of taxpayer liability on a return or claim for refund is due to negligent or intentional disregard of rules and regulations. A preparer is not required to obtain supporting documentation unless he has reason to suspect the accuracy of the taxpayer's figures; however, the preparer must make reasonable inquiries if the taxpayer's information appears incorrect or incomplete.Choices "c", "b", and "d" are incorrect, per the above rule.