Each of the following constitutes substantial authority for a taxpayer to take a tax position, except: A. A determination letter conclusion in which the taxpayer is named. B. A technical advice memorandum conclusion in which the taxpayer is named. C. An affirmative statement in a revenue agent's report with respect to a prior year of the taxpayer. D. A private letter ruling in which the taxpayer is named and that is inconsistent with a subsequently issued Treasury Regulation