Sentence Correction

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) world in that a sacred truce was proclaimed
during the festival's month
(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

D should be correct.