Change In Accounting Period. In which of the following instances is a taxpayer permitted to change accounting

Question:

Change In Accounting Period. In which of the following instances is a taxpayer permitted to change accounting periods without IRS approval?
a. A calendar-year taxpayer who wishes to change to a year that ends on the last Friday in December.
b. ABC has filed its tax return using a fiscal-year ending on March 31 for over 40 years. The wishes to change to a calendar year-end that coincides with its partners' year-end.
c. Iowa Corporation, a newly acquired subsidiary, wishes to change its year-end to coincide with its parent.
Partnership
A legal form of business operation between two or more individuals who share management and profits. A Written agreement between two or more individuals who join as partners to form and carry on a for-profit business. Among other things, it states...