单项选择题

C Co uses material B, which has a current market price of $0·80 per kg. In a linear program, where the objective is to maximise profit, the shadow price of material B is $2 per kg. The following statements have been made: (i)Contribution will be increased by $2 for each additional kg of material B purchased at the current market price (ii)The maximum price which should be paid for an additional kg of material B is $2 (iii)Contribution will be increased by $1·20 for each additional kg of material B purchased at the current market price (iv)The maximum price which should be paid for an additional kg of material B is $2·80 Which of the above statements is/are correct