Answer:
D: Slaves and Vikings
D Explanation
Slaves were basically the people whose descendants are Russian, Belarusian, Serbian, and more.
After Ivan the Great drove off the Mongols, the Slavs in Kiev, today the capital of Ukraine, asked the Vikings to rule them since they proved they couldn't do it themselves.
A Explanation:
Celts were polytheist people in Ireland, which is nowhere close at all to Russia
B Explanation:
Where's the Slaves?
C Explanation:
Again... Where's the Slaves
Hopefully this helped, if not HMU and I will try my best o get you a better answer! :)