Answer:
b. list the average amount.
Step-by-step explanation:
If your income varies, you should "list the average amount".
When a particular set of values vary, an average value is used. Average value is actually the estimated value which is found in two or more varying values. It gives an idea of what an expected value will be.
So, when income varies, the average amount is expected to be listed. This is done in order compensate even the lowest amount. So if two income varies, the average amount can be determined by adding the highest amount to the lowest amount, and dividing the outcome by 2.