The correct answer is A. 5%.
Interest on calls in arrears is charged at 5% per annum. This means that if you have not paid a call on a share, you will be charged 5% interest on the amount of the call that you have not paid. This interest is payable on the next call date.
For example, if you have not paid a call of $100 on a share, you will be charged $5 interest on the next call date. This interest will be added to the amount of the call that you owe, so you will then owe $105.
Interest on calls in arrears is a way of encouraging shareholders to pay their calls on time. If you do not pay your calls on time, you will be charged interest, which will increase the amount of money that you owe. This can be a significant amount of money, so it is important to pay your calls on time.
The other options are incorrect because they do not represent the correct interest rate on calls in arrears.