Final answer:
Annual usage in the context of inventory classification refers to the percentage of a product's inventory that is sold within a year.
Step-by-step explanation:
In the context of inventory classification, the term annual usage refers to option c) the percentage of a product's inventory that is sold within a year. This is a measure of how quickly a product is being sold and helps businesses manage their inventory levels. It is calculated by dividing the number of units sold within a year by the average inventory level for that year, and then multiplying by 100.