4. A uniform price auction is an auction where all the winners pay the same price. A k-th price auction is an auction where the price paid by the winner(s) is the k-th highest bid. We run a 3rd price, uniform price auction for two items, so the winners are the two bidders with the highest bid. There are 4 bidders, A, B, C and D, and they bid respectively $10, $9, $8 and $12. (1 point) (A) Bidders A and B win the auction and pay $9. (B) Bidders A and D win the auction and pay $9. (C) Bidders B and D win the auction and pay $10. (D) Bidders B and C win the auction and pay $8