You sell one December futures contracts when the futures price is $1,010 per unit. Each contract is on 100 units and the initial margin per contract that you provide is $3,000. The maintenance margin per contract is $2,000. During the next day the futures ptice rises to $1,017 per unit. What is the balance of your margin account at the end of the day? $3,700 $3,300 $2,300 $1,800