Explanation
Matching the Sea with a Country bordering it:
1. A. Black Sea - Bordered by several countries including Romania, Ukraine, Russia, Georgia, Turkey, and Bulgaria. So, A matches with 1.
2. B. Red Sea - Bordered by countries including Egypt, Sudan, Eritrea, Djibouti, Yemen, and Saudi Arabia. So, B matches with 3.
3. C. Yellow Sea - Located between mainland China and the Korean Peninsula. So, C matches with 2.
4. D. Caspian Sea - Bordered by Russia, Azerbaijan, Iran, Turkmenistan, and Kazakhstan. So, D matches with 4.
Therefore, the correct matching sequence is A-1, B-3, C-2, D-4.