Dutch auction for $80 billion of US Treasury bills. Noncompetitive Bids total $20 billion, and competitive bidders in descending order of offer price are as giv table. Competitive Bids (in billions) Discount Rate Bid Bid Price per $100 0.0280% 99.99782 0.0285% 99.99778 0.0287% 99.99777 0.0290% 99.99774 0.0291% 99.99774 0.0292% 99.99773 0.0291% 99.99773 What is the discount rate necessary to sell all amount of Treasury bills? $5 $10 $15 $30 $45 $15 $10