I'll first explain what the non-aggression pact was. It was an agreement that the Soviet Union and Germany would take no military action against each other. To answer your question it is B. The pact was to make sure he could safely attack Poland.
Your answer should be C.
They aren't necessarily cheaper, nor does it matter about the quantity, they also don't help the land much.
I believe your answer is it established the final boundery between british canada and the U.S.
Hope this helps
