The Olympic Games helped to keep peace among the pugnacious states of the Greek world in that a sacred truce was proclaimed during the festival's month.
(A) Same
(B) world, proclaiming a sacred truce during the festival’s month
(C) world when they proclaimed a sacred truce for the festival month
(D) world, for a sacred truce was proclaimed during the month of the festival
(E) world by proclamation of a sacred truce that was for the month of the festival
OG says, the correct choice is (D). Please help to understand why (D) is correct. I was more inclined towards (B) as in (B) proclaiming is modifying the clause successfully.
OG's explanation says - It is not clear who would be doing the proclaiming; a clause is preferable to phrase. Please help understand why?
Thanks
GMAT 2007