一道GWD削弱题，答案是C，请教高手原因！祝大家新年快了！！

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?

1. Because steel from Krenland is rarely competitive in international markets, only a very small portion of Krenlandian steelmakers’ revenue comes from exports.
2. The international treaties that some governments are violating by giving subsidies to steelmakers do not specify any penalties for such violations.
3. 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.
4. 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.
5. 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.

不太明白啊

请您详细解释一下好吗？

C是说钢铁的成本对很多工业很重要。

注意原文的结论是，采取措施减少钢铁进口不仅保护了钢铁企业还保护了工业人口的就业。

如果C成立，那么采取措施减少钢铁进口将提高许多企业的成本，这使得许多企业不能生存下去，于是乎这些企业的原员工将面临失业。

这个题干本身推理最大的弱点就在于没有任何理由的把所有工业就业都加进去了（要知道，诚然保护了钢铁企业的工人就业但是对整体就业却没好处），属于扩大范围的错误。