The Protestant Reformation was a major 16th century European movement aimed initially at reforming the beliefs and practices of the Roman Catholic Church. Its religious aspects were supplemented by ambitious political rulers who wanted to extend their power and control at the expense of the Church.
I do not believe women or slaves could become citizens.

This sentence gives no reason to add any commas what so ever. This would be a straight forward run-on sentence that would need no clause, pauses or anything that would break this sentence down any more.
Option B would give clear and straight forward information. The first option broke this sentence down as we can see, and as for this, this would not be the proper way of expressing this sentence. Therefore, your
last option would then be your answer.
Answer:
The answer to your question is containment which helps its allies to prevent the spread of communism. Hope it helps!