Which geographic feature marks the easternmost edge of Islam under the Umayyads?

a. black sea

b. indus river valley

c. nile river

d. sahara desert

The answer is B. Indus River Valley.

Indus River Valley marks the easternmost edge of Islam under the Umayyads. The Umayyad Caliphate was the second caliphate out of the four major caliphates that was established after Muhammad's death. The Umayyad dynasty rules the Umayyad Caliphate.