Consider the following pairs:River Flows into1.Mekong : Andaman Sea2.Thames : Irish Sea3.Volga : Caspian Sea4.Zambezi : Indian OceanWhich of the pairs given above is/are correctly matched?

1. A

   1 and 2 only

   1 and 2 only. Mekong meets the South China Sea (Vietnam), not the Andaman Sea; Thames is the North Sea, not the Irish Sea.

2. B

   3 only

   3 only. Zambezi also holds.

3. C

   3 and 4 only

   3 and 4 only. Volga → Caspian; Zambezi → Indian Ocean (Mozambique Channel). Mekong and Thames are mis-paired.

4. D

   1, 2 and 4 only

   1, 2 and 4 only. Keeps two wrong seas.

Summary. Official key is (c) 3 and 4 only. Volga drains to the Caspian; Zambezi to the Indian Ocean. The Mekong delta is South China Sea; the Thames estuary is the North Sea.