Which one among the following is a landlocked water body ?

The Caspian Sea is the correct answer because it is the world's largest inland body of water and is entirely surrounded by land, making it a landlocked water body. It is bordered by five countries: Kazakhstan, Russia, Azerbaijan, Iran, and Turkmenistan, and has no natural outlet to the world's oceans.

In contrast, the other options have natural oceanic connections:

• Mediterranean Sea: Connects to the Atlantic Ocean via the Strait of Gibraltar.
• Black Sea: Connects to the Mediterranean Sea through the Bosphorus and Dardanelles straits.
• Red Sea: Connects to the Indian Ocean via the Bab-el-Mandeb strait and the Gulf of Aden.

Geographically, while called a "sea" due to its massive size and saline water, the Caspian Sea is technically an endorheic basin (a drainage basin that retains water and allows no outflow to other external bodies of water).