【单选题】Auctions are public sales of goods, conducted by an officially approved auctioneer. He asks the crowd assembled in the auction-mom to make offers, or 'bids', for the various items on sale. He encourag...
A.
because they took place at night
B.
as a signal for the crowd to gather
C.
to keep the auctioneer warm
D.
to limit the time when offers could be made