4．The price the government pays for standard weapons purchased from military contractors is determined by a pricing method called＂historical costing．＂Historical costing allows contractors to protect their profits by adding a percentage increase，based on the current rate of inflation，to the previous year’s contractual price．
Which of the following statements，if true，is the best basis for a criticism of historical costing as an economically sound pricing method for military contracts? (A) The government might continue to pay for past inefficient use of funds．
(B) The rate of inflation has varied considerably over the past twenty years．
(C)The contractual price will be greatly affected by the cost of materials used for the products．
(D) Many taxpayers question the amount of money the government spends on military contracts．
(E) The pricing method based on historical costing might not encourage the development of innovative weapons．
og解释C： Identifying the importance of the cost of materials，which also varies with inflation，is a strength of the method． 我实在是不能够理解，既然the cost of materials also varies with inflation，那为什么不可以作为一个不能使用historical costing 的理由？ | 
