sc should - important

[demoskopico]

Until quite recently, American economists have assumed that the unemployment rate being four per cent, there is a rough balance among jobs and job seekers.

(A) the unemployment rate being four per cent, there is a rough balance among jobs and job seekers
(B) should the unemployment rate be four per cent, there is a rough balance among jobs and job seekers
(C) were the unemployment rate four per cent, there is a rough balance between jobs and job seekers
(D) if the unemployment rate is four per cent, there is a rough balance between jobs and job seekers
(E) there is a rough balance among jobs and job seekers when there is an unemployment rate that is four per cent