What Does It Mean If an Auction Is with Reserve

Multiple Choice

What does it mean if an auction is with reserve?

A) Unless otherwise stated,the auctioneer has the right to withdraw the item before the fall of the hammer.
B) The auctioneer must sell to the highest bidder.
C) Even after the fall of the hammer,the auctioneer can accept other bids.
D) The items for sale have a minimum price.