The Ottoman Turks Were Able to Begin to Amass Territory

Multiple Choice

The Ottoman Turks were able to begin to amass territory in the fourteenth century because:

A) the Mongols had toppled the older powers that had traditionally kept them in check.
B) the Byzantine empire had fallen.
C) they had acquired artillery from China.
D) they had allied themselves with the sultanate of Rûm.
E) the Abbasid caliphate had hired them as mercenaries.