Choice "D" is correct. The accumulated earnings tax can be imposed on regular corporations not classified as personal holding companies.
Choice "c" is incorrect. The accumulated earnings tax can be imposed on regular corporations (C corporations) or on personal service corporations.
Choice "a" is incorrect. The accumulated earnings tax may be imposed on a corporation whose accumulated (retained) earnings is in excess of $250,000 (less for personal service corporations) and for which no justified reason for the retention exists.
Choice "b" is incorrect. A parent-subsidiary group is not a requirement for the imposition of the accumulated earnings tax.