Option 3 is the correct answer, pairing each sea with the correct country. In this option, A-1 indicates that the Black Sea is connected with Bulgaria, which is accurate as Bulgaria is one of the six countries bordering the Black Sea. B-3 suggests that the Red Sea corresponds to Eritrea, and indeed Eritrea is located along the Red Sea. Furthermore, C-2 indicates that the Yellow Sea is related to China, which is correct as the Yellow Sea is an arm of the Pacific Ocean lying between mainland China and the Korean Peninsula. Lastly, D-4 means the Caspian Sea is associated with Kazakhstan; this also true as Kazakhstan has a significant portion of its territory on the eastern coast of the Caspian Sea. The other options listed offer incorrect pairings.