Afghanistan is separated from Central Asia by:_________?

A. Caspian Sea
B. Wakhan
C. Aral River
D. Oxus River

Afghanistan is separated from Central Asia by Oxus River.
The Amu Darya (also called the Amu, Amo River, or Amudaryo, and historically known by its Latin name Oxus is a major river in Central Asia and Afghanistan. Rising in the Pamir Mountains, north of the Hindu Kush, the Amu Darya is formed by the junction of the Vakhsh and Panj rivers, in the Tigrovaya Balka Nature Reserve on the border between Afghanistan and Tajikistan, and flows from there north-westwards into the southern remnants of the Aral Sea. In its upper course, the river forms part of Afghanistan’s northern border with Tajikistan, Uzbekistan, and Turkmenistan.