Online auctions are: a. cost-effective for selling excessive inventory. b. based on the barter business model. c. used to bring buyers and sellers together in a real marketplace. d. useful when goods already have a set price in the marketplace

The correct answer is letter "A": cost-effective for selling excessive inventory.

Explanation:

Online auctions work very similarly than physical auctions where buyers and sellers set the price of goods based on bids they place to them when there is no set price. By making auctions available online, auctions open up their doors to buyers from anywhere around the world.

Online auctions are said to be cost-effective for excessive inventory sales since major quantities of items can be offered in batches where only one buyer can purchase all those items in one transaction.