Which of the following can be inferred about supplier partnerships, as they are described in the passage?
A.
They cannot be sustained unless the goods or services provided are available from a large number of suppliers.
B.
They can result in purchasers paying more for goods and services than they would in a competitive-bidding situation.
C.
They typically are instituted at the urging of the supplier rather than the purchaser.
D.
They are not feasible when the goods or services provided are directly related to the purchasers’ end products.？？？？
E.
They are least appropriate when the purchasers’ ability to change suppliers is limited.
为什么D是错误的呢？ 原文是：In corporate purchasing, competitive scrutiny is typically limited to suppliers of items that are directly related to end products. With “indirect” purchases (such as computers, advertising, and legal services), which are not directly related to production, corporations often favor “supplier partnerships” (arrangements in which the purchaser forgoes the right to pursue alternative suppliers), which can inappropriately shelter suppliers from rigorous competitive scrutiny that might afford the purchaser economic leverage | 
