Auctions (拍卖) are public sales of goods, conducted by an officially approved auctioneer. He asked the crowd to gather in the auction room to bid (出价，喊价) for the various items on sale. He encourages buyers to bid higher figures, and finally names the highest bidder as the buyer of the goods. This is called "knocking down" the goods, for the bidding ends when the auctioneer bangs a small hammer on a raised platform.The ancient Romans probably invented sales by auction, and the English word comes from the Latin "auction", meaning "increase". The Romans usually sold in this way the spoils taken in war; these sales were called "sub hasta", meaning "under the spear (矛)", a spear being stuck in the ground as a signal for a crowd to gather. In England in the eighteenth and nineteenth centuries goods were often sold "by the candle"; a short candle was lit by the auctioneer, and bids could be made while it was burning.Practically all goods can be sold by auction. Among these are coffee, skins, wool, tea, cocoa, furs, fruit, vegetables and wines. Auction sales are also usual for land and property, antique furniture, pictures, rare books, old china and works of art. The auction rooms at Christie’s and Sotheby’s in London and New York are world famous.An auction is usually advertised beforehand with full particulars(细节)of the articles to be sold and where when they can be viewed by the buyers. If the advertisement cannot give full details, catalogues are printed, and each group of goods to be sold together called a "lot", is usually given a number. The auctioneer need not begin with Lot One and continue the numerical order, he may wait until he notices the fact that certain buyers are in the room and then produce the lots they are likely to be interested in. The auctioneer’s services are paid for in the form of a percentage of the price the goods are sold for. The auctioneer therefore has a direct interest in pushing up the bidding. The end of the bidding is called "knocking down" because（）

A. the auctioneer knocks on the table
B. the auctioneer names the highest bidder as the buyer of the goods
C. the goods are knocked down onto the table
D. the auctioneer bangs the table with a hammer