When Using the Unpaid or Previous Month's Balance Method

When using the unpaid or previous month's balance method:

A) the billing cycle is always 30 or 31 days
B) you should first multiply the unpaid or previous month's balance by the monthly rate
C) the first step in calculating the new unpaid balance is to determine the purchases for the period and then add them to the previous balance
D) the average daily balance is the same as the unpaid balance