Bill, Bob and Betty are equal partners in BBB partnership. Bill uses the calendar year end, Bob uses a fiscal year ending May $31$st and Betty uses a fiscal year ending August $31$st$.$

Required:

What is the required year end of the partnership? Explain each of the three rules $($why or why not they are applicable here$)$ and which one the partnership must use to determine its tax year. $($Show your work$)$