X, Y and Z form a partnership, X is a corporation with a 7/31 fiscal year, Y is a corporation with a 1/31 fiscal year, and Z is a calendar year individual. What is the partnership's required taxable year if the partners share profits and capital in the following alternative proportions.

a) 60% X, 20% Y, 20% Z

b)50% X, 30% Y, 20% Z

c) Assume the XYZ partnership's principal business activity is the preparation of tax returns. What taxable year might it prefer? Is that choice available to it?