Which of the following can be inferred about supplier partnerships, as they are described in the passage?

1. They cannot be sustained unless the goods or services provided are available from a large number of suppliers.

2. They can result in purchasers paying more for goods and services than they would in a competitive-bidding situation.

3. They typically are instituted at the urging of the supplier rather than the purchaser.

4. They are not feasible when the goods or services provided are directly related to the purchasers’ end products.

5. They are least appropriate when the purchasers’ ability to change suppliers is limited.

原文：

我也是很困惑,觉得D没有问题,但是考试要求我们选择最好的,比较一下,B在文中有原文可以对应找到,D在原文没有直接说明,可能DIRECT PRODUCT也可以用PARTNERSHIP,我们不能做推断.

文章中对应于B的地方是否就是which can inappropriately shelter suppliers from rigorous competitive scrutiny that might afford the purchaser economic leverage.？

这句话表明这种合作关系对于供应者来说是好的，否则他就要在激烈的市场上去打拼了。由此推断，有了这个关系以后，他的价格可能会卖的高一些。

(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.

表示买家没有选择余地，表示可以防止卖家之间的竞争，是说对卖家的好处，economic leverage是指讨价还价的余地，说的是对买家的坏处。

至于D选项， With “indirect” purchases (such as computers, advertising, and legal services), which are not directly related to production, corporations often favor “supplier partnerships”。原文用的是often favor,选项太绝对。 

正说成立-competitive scrutiny is typically limited to suppliers of items that are directly related to end products；反说就不一定成立啊 -  supplier partnerships is not feasible when the goods or services provided are directly related to the purchasers’ end products. 

文章通篇围绕着competitive scrutiny的适用性来讨论的，并没有说明supplier partnerships在什么情况下不适用。

文章第一句只是是说competitive scrutiny is typically limited，但没讲就不用 supplier parnership了。第二句说“indirect” purchases更favor supplier partnership,但不是说只有在这种情况下才用。所以D不对。B否不能推A否

B是对的，因为：“supplier partnerships” (..)which can inappropriately shelter suppliers from rigorous competitive scrutiny that might afford the purchaser economic leverage.