Which country has closed off Bosphorus and Dardanelles straits to limit transit of Russian warships to the Black Sea?

A. Bulgaria

B. Turkey 

C. Ukraine

D. Romania

Explanation:

NATO ally Turkey has closed off the Bosphorus and Dardanelles straits in the Black Sea to warships from any country to potentially limit the transit of Russian warships from the Mediterranean to the Black Sea. Turkey shares a maritime border with both Russia and Ukraine in the Black Sea. The other countries bordering the Black Sea include Bulgaria, Georgia, and Romania.