Because the management of a large corporation will often refer to macroeconomic forecasts when it plans for the future,
it is probable that its belief in their soundness is significant.
Meaning : because Management will OFTEN refer to forecasts, it is likely that the managements thinks of the forecasta as significant. Or why wpuld it refer to forecasts OFTEN??
Structure :
Subordinate clause : Because management (singular)will refer to ... forecasts(plural)
main clause: it (placeholder) that its (management's) belief in their(forecasts) is signicant (belief is the subject / is - verb)
Quote:
(A) it is probable that its belief in their soundness is significant.
The empty it though right grammatically unnecessarily makes the sentence wordy. Keep it until you find a better one.
Quote:
(B) it is probable that the soundness of their belief would significant.
their(forecasts) ...forecasts do not have a belief
Quote:
(C) believing their soundness is probably not significant.
"comma+ verbing " modifies preceding main clause. As the preceding structure is a subordinate clause, this choice makes the sentence a fragment
Quote:
(D) the significance of their belief on its soundness is probable.
same error as B
Quote:
(E) its belief in their soundness is probably significant.
management's belief in forecasts' soundness is probably significant. CLear and concise and not WORDY as A.