Under what circumstances is a taxpayer required to use a calendar year tax period? A) If the taxpayer does not keep books or accounting records. B) If the taxpayer just opened a new business. C) If the taxpayer has a tax year of less than 12 months. D) If the taxpayer receives reporting documents such as Forms W-2 and 1099.

Dalton CFP Mid-Term for Income Tax Planning says "C" is wrong. What is it?