The question under discussion here is ______ of the "white pollution".

     A. that       B. which     C. one          D. it

The question under discussion here is ______ of the "white pollution".

     A. that       B. which     C. one          D. it

The question under discussion here is ______ of the "white pollution".

     A. that       B. which     C. one          D. it

The question under discussion here is ______ of the "white pollution".

     A. that       B. which     C. one          D. it

 The question under discussion here is ______ of the “white pollution”. 

A. that          B. which            C. one              D. it

 The question under discussion here is ______ of the "white pollution".

     A. that       B. which     C. one          D. it

The question under discussion here is ______ of the "white pollution".