The answer is a) divided by number of days in billing cycle
Explanation:
The average daily balance is the average amount of money held in an account during the month. All financial institutions use it to calculate the annual effective rate and maintenance costs. Its calculation is as follows: the sum of the balance held in the account at the close of each day and then divided by the number of days in the month. This way you have:
Average daily balance = Sum of daily balances in the account/number of days per month