Look closely at this map. In ancient times, Greece and Persia (present-day Iran) fought to control the Dardanelles and Bosphorus straits. Russia fought Turkey over these straits in the 1800s, and the Allies (France, Russia, and the United Kingdom) invaded them during World War I.
Which of the following is the most likely reason so many powers have considered these straits worth fighting over?
The straits control access to ports in the Black Sea.
hope this helps