请教一道不知出处的题

这题是我从网上当下来的一套题里的，据说是最新题。答案选a，我选c.理由是：sth of sth>sth's sth; especially表程度上的“尤其的，特别的”，specially没有这层意思。想请大家帮我看看，我的想法对不对？

Sulfur dioxide, a major contributor to acid rain, is an especially serious pollutant because
it diminishes the respiratory system’s ability to deal with all other pollutants.
A. an especially serious pollutant because it diminishes the respiratory system’s
ability to deal
B. an especially serious pollutant because of diminishing the respiratory system’s
capability of dealing
C. an especially serious pollutant because it diminishes the capability of the
respiratory system in dealing
D. a specially serious pollutant because it diminishes the capability of the respiratory
system to deal
E. a specially serious pollutant because of diminishing the respiratory system’s
ability to deal

GWD10-8

這是出自於GWD的第十回第八題，解這一題是先看especially與specially，做adv使用時，especially優先於specially

其次 to deal with優先於 in dealing with，看一下respiratory system's ability沒有太大問題，就可以選A了

你可能會說system沒有生命，但請注意，respiratory system是呼吸系統，語意及語法上是沒問題的