Who signed the non aggression pact ?

Explanation:

Nazi Germany and the Soviet Union agreed not to take any military action against each other, whether solely or combining with other powers for the next 10 years.

They also agreed not to support any third party that might attack the other party in contract. They should encourage each other touching their common interests and solve their problems  by negotiation or arbitration.

After 10 years, the pact will get automatic extension for next 5 years. Any party that wants to terminate the pact should give notice 1 year before its expiration.

the answer would be:

b. race