Final answer:
Profit income refers to the income earned from the sales of products or services after deducting the expenses associated with producing them.
Step-by-step explanation:
The income received from selling Mia's books is an example of profit income. Profit income refers to the income earned from the sales of products or services after deducting the expenses associated with producing them. In Mia's case, the income she receives from selling her books is the revenue generated from the sales, minus any costs incurred in writing, editing, publishing, and distributing the books.