What Ultimately Contributed to the Weakening of the Persian Empire

Multiple Choice

What ultimately contributed to the weakening of the Persian Empire?

A) The kings' excessive taxation and hoarding of wealth
B) The use of citizens as soldiers
C) The growing resentment among Persian subjects over the Great King and his power over life and death
D) The failure of the military to conquer advancing enemies
E) The defeat of the Persians on the banks of the Tigris River