Zee Corp is a March 31 fiscal year C Corp. It owns 75% of XYZ partnership. Leah a calendar year individual owns the other 25% of XYZ.

a) Suppose instead the RST partnership is owned by the following partners: R and S each own 24% and they have a January 31 fiscal year-end. The remaining 52% is owned equally by partners A through M (so each owns 4%). A B, C, and D have a 3/31 fiscal year-end. E, F, G, and H have a 6/30 year-end. I, J, K, and L have a 9/30 fiscal year-end and M is a calendar year individual. What tax year can RST elect?

b) A, B, and C are equal partners in the ABC partnership, each owning one-third. A's is a calendar year individual. B is a corporation with a fiscal year-end of 4/30. C is an estate with a fiscal year-end of 8/31. What year-end can ABC elect? (hint, the answer may require complex calculations so just give the name of the concept.