Editorial in Krenlandian Newspaper:

Krenland’s steelmakers are losing domestic sales because of lower-priced imports, in many cases because foreign governments subsidize their steel industries in ways that are banned by international treaties. But whatever the cause, the cost is ultimately going to be jobs in Krenland’s steel industry. Therefore, it would protect not only steel companies but also industrial employment in Krenland if our government took measures to reduce cheap steel imports.

Which of the following, if true, most seriously weakens the editorial’s argument?

A. Because steel from Krenland is rarely competitive in international markets, only a very small portion of Krenlandian steelmakers’ revenue comes from exports.

B. The international treaties that some governments are violating by giving subsidies to steelmakers do not specify any penalties for such violations.

C. For many Krenlandian manufacturers who face severe international competition in both domestic and export markets, steel constitutes a significant part of their raw material costs.

D. Because of advances in order-taking, shipping, and inventory systems, the cost of shipping steel from foreign producers to Krenland has fallen considerably in recent years.

E. Wages paid to workers in the steel industry in Krenland differ significantly from wages paid to workers in many of the countries that export steel to Krenland.

考虑了良久以后选了D，没有选C，结果答案是C。请大家帮我分析一下

最后结论提出：it would protect not only steel companies but also industrial employment in Krenland。即有两个好处。一个是保护钢铁行业，一个是本地就业。C项暗示目前的低价进口钢铁原料对本土的制造商维系竞争优势有好处，那一个后果就是牺牲本地的钢铁企业为代价了。此外，C暗示的也不见得能保护本地的就业，因为它还有一点没有说明白，就是到底谁，是manufacturers还是steelmakers雇佣的人多，因为若是steelmakers雇佣的人多的话，那么的确就对本地的就业构成威胁，如果，是制造商雇佣人数多的话，那么C项描述的才成立。所以，从上述两个方面，我认为C都没有对结论构成削弱，反而有点偏离了scope。

之所以选了D，是这样思考的，请大家帮助指正分析过程中的错误：even if our government subsidizes the steel corps, the companies and employments are still not be protected, because other factors still can lead the same result. C项所述就很好的满足了这个条件：即便本地政府同样采用补贴的方式，也不见得能保护钢铁行业和就业。因为，外来的低价钢材的优势可以是其他因素造成的。从而对结论构成威胁。

我到底哪里错了呢？请不吝赐教，谢谢

Conclusion: it would protect not only steel companies but also industrial employment  (industrial employment does not refer to jobs only in steel industry but in all kinds of industries) in Krenland if our government took measures to reduce cheap steel imports.

please pay due attention to the bold face portion...how can a reduction of cheap steel imports protect industrial employment?

In order to meet the problem's requirement "weaken", we have to prove that such reduction can not necessarily protect industral employment.

C. For many Krenlandian manufacturers who face severe international competition in both domestic and export markets, steel constitutes a significant part of their raw material costs. C tells that steel is a major raw material for Krenlandian manufactures's production activities.
   

Under the circumstances of C, if such a reduction of cheap imported steel were in effect, the domestic steel price would be bound to rise and the costs to  Krenlandian manufactures would be very likely to soar.  And therefore those manufactures would suffer from decline in profits and loss from competitive advantage, and even would be forced to get out of market. There is no doubt that industrial employment will not be protected but be hurt by such a reduction.

Does my explanation make sense?

补充一下：

industrial employments 指的不仅仅包括steel industry还有其他工业领域的比如说建筑业 机械制造行业的jobs..

为什么钢材的进口禁止会影响整个工业领域的就业呢？ 而不仅仅影响的是钢铁行业的就业。