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.
To help other people realize something that might not be common sense to them.
the answer to your problem is the greeks and romans
In World History, a declaration of independence does exactly that: declare a country's independence from a mother country. For example, the United States declared independence from England, and Comoros declared independence from France.