Answer: A.) December
Step-by-step explanation:
December has the highest number of days in the options given above, with 31 days compared to the others with 30 days within a calendar month. The billing cycle is used to refer to a time interval between the end and the next billing or statement date. In the scenario above, the billing cycle length is monthly, meaning the periodic interest will be paid over a 31 day span time before thre beginning of another cycle.
For example, if periodic interest is $1 per day, this amount totals ($1 × 31) in december compared to the ($1 × 30) Interest in the June, April and September billing cycle.