Option 1: Yangtze Kiang - East China Sea

This is a correct match. The Yangtze Kiang is a major river in China that flows into the East China Sea.

Option 2: Euphrates - Aral Sea

This is an incorrect match. The Euphrates is a river in Western Asia that does not flow into the Aral Sea. The Euphrates flows through Iraq and Syria, and eventually merges with the Tigris River before flowing into the Persian Gulf.

Option 3: Lena - Arctic Ocean

This is a correct match. The Lena River is located in Russia and it flows into the Arctic Ocean.

Option 4: Mekong - Japan Sea

This is an incorrect match. The Mekong is a river in Southeast Asia that does not flow into the Japan Sea. The Mekong flows through several countries including China, Myanmar, Laos, Thailand, Cambodia, and Vietnam before emptying into the South China Sea.

Therefore, the correctly matched pairs are Yangtze Kiang - East China Sea and Lena - Arctic Ocean. The correct answer is option 3.