OG11, key is D? but i think B ??

tanwt

. 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     （D）

(E) world by proclamation of a sacred truce that was for the month of the festival

tanwt

the explaination says for joins two sentence:

D. Correct. In this sentence, the conjunction for joins the two clauses correctly and economically

??????