OG10-198

A factory was trying out a new process for producing one of its products,with the goal of reducing production cost.A trail production run using the new process showed a 15% reduction in costs compared with past performance using standard process.The production managers therefore concludeed that the new process did produce a cost saving.

Which of the following,if true,cast most doubt on the production manager's conclusion.

对c：while the trial was being conducted,production cost s at the factory for a samilar product,produced without benefit of the new process,also showed a 15% reduction.

错b:Analysis of the trail of the new process showed that the cost reduction during the trial was entirely attributable to a reduction in the number of finished products rejected by quality control.

题目说“process for producing one of its products”降低15%cost manager因此说the new process did produce a cost saving.

我认为C说另一个产品没用这个流程也“showed a 15% reduction.”是无关选项，因为题目说的是“one of its products” 而选项却说另一个类似的产品

我选b因为流程省下的“ a 15% reduction in costs”不合格“rejected by quality control.”

请帮我解释一下我哪想错了？谢谢！