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 true 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 is (C). The explanation says this sentence deals in the incorrect usage of the conjunction used to connect two independent clauses. And ‘for’ is the correct conjunction to join these two sentences because second clause explains the first one.
Explanation also says (B) is incorrect because it is not clear who is doing the proclaiming. The clause is preferable to a phrase.

My question – Is (B) incorrect because the participial phrase starting with ‘proclaiming’ doesn’t clearly point to ‘The Olympic games’? In case we change the sentence as –

Proclaiming a sacred truce during the festival’s month, 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. In this case would participial phrase modify the Olympic Games correctly?

Thanks

Correct answer is D, not C.

The Olympic Games cannot proclaim anything; people proclaim things. B seems to imply that the Games are proclaiming, but that doesn't make sense.

In D, it says (passively) "a sacred truce was proclaimed" - so now we know that the unnamed people behind the Games proclaimed the sacred truce, etc.