Explanation:

- To reach the Black Sea from the Atlantic Ocean, a common sea route is: Atlantic Ocean ? Strait of Gibraltar ? Mediterranean Sea ? Aegean Sea ? Strait of Dardanelles ? Sea of Marmara ? Bosporus Strait ? Black Sea.

- Option 1 involves the Dardanelles, Marmara Sea, and Bosporus Strait, which are actual parts of the route.

- Option 2, the Adriatic Sea, is an arm of the Mediterranean and not on the direct path to the Black Sea.

- Option 3, the Aegean Sea, is on the path as it connects to the Dardanelles.

- Option 4, the Strait of Gibraltar, is the gate from the Atlantic to the Mediterranean.

- Correct Answer: Option 2, Adriatic Sea