Choice "C" is correct. For an opinion to be a covered opinion, the opinion can be limited to just some of the significant federal tax issues if the practitioner and the taxpayer agree that the opinion will be limited and that the taxpayer's reliance on the opinion for the purpose of avoiding penalties will be similarly limited.Choice "d" is incorrect. For an opinion to be a covered opinion, the opinion need not consider all significant federal tax issues (e.g., those raised in the item and transaction, property, partnership, plan, or arrangement issues). The opinion can be limited. Choice "b" is incorrect. For an opinion to be a covered opinion, the opinion can be limited to just some of the significant federal tax issues, but there is no requirement that the opinion consider at least 50% of all of the significant federal tax issues.Choice "a" is incorrect. For an opinion to be a limited opinion, it need not be limited to only one of the significant tax issues. Significant tax issues must be sufficiently and clearly covered, but it is not necessary to cover only one significant tax issue at a time to do that.