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.

1. an especially serious pollutant because it diminishes the respiratory system’s ability to deal
2. an especially serious pollutant because of diminishing the respiratory system’s capability of dealing
3. an especially serious pollutant because it diminishes the capability of  the respiratory system in dealing
4. a specially serious pollutant because it diminishes the capability of  the respiratory system to deal
5. a specially serious pollutant because of diminishing the respiratory system’s ability to deal

答案是a,我选d。。。

especially特别地

 specially 专门的

specially 的解释：

1.for one particular purpose, and only for that purpose
specially trained police dogs specially designed/built/made etc The boats are specially built for the disabled.
2.(spoken) much more than usual, or much more than other people or things
——synonym especially

He specially liked the pie.
see usage note especially