C, because it is bounded to the west by the Black Sea
They are divided into degrees so that we can know the exact location :)
The Black Sea is a main body of water separating Europe and Asia.
Religious and ethnical problems.
It was one of the largest empires of the world with many different ethnicities. The problem was to unite people under one rule.
Another problem was communication. It was hard to transfer knowledge and news to all parts of the empire because it was too large.