In a Sealed-Bid Auction

In a sealed-bid auction:

A) buyers bid against each other with a succession of increasingly higher prices until only one remains.
B) a bid is announced, and if no buyer accepts the bid in a given period of time, a new, slightly lower, bid is announced; this procedure continues until a bidder accepts the announced price.
C) each bidder submits a price that is known only to that bidder; bids are opened and the highest (lowest) bid is accepted.
D) each bidder submits a price that is known only to that bidder; bids are opened and the highest (lowest) bidder wins, but the transaction occurs at the second highest (lowest) price.
E) none of the above.