Believed by many leaders is that, in order for our nation to achieve financial solvency, each of our millions of citizens has to seek financial solvency, because a nation can be only as solid as its citizens.
(A) Believed by many leaders is that, in order for our nation to achieve financial solvency, each of our millions of citizens has :
Sounds wrong but rest all are ok grammatically. Lets keep it(B) So that our nation achieves financial solvency, many leaders believe that all of our millions of citizens has :
Wrong Idiom use of SO THAT(C) It is believed by many leaders that, for our nation to achieve financial solvency, each of our millions of citizens who has
: 'It' has no antecedent but it could be a place holder too. Passive voice is an issue here. (D) Many leaders believe that, in order for our nation to achieve financial solvency, every one of our millions of citizens have
: Each/every/everyone are singular and hence HAS should be used and not have. (E) So that our nation will achieve financial solvency, many leaders believe that each of our millions of citizens has
: Wrong Idiom useHence A is our answer.