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 | 
