Money existed in the form of labor - each subject of the empire paid "taxes" by laboring on the roads, crop terraces, irrigation canals, temples, or fortresses. In return, rulers paid their laborers in clothing and food. Silver and gold were abundant but only used for looks. Inca kings and nobles had many riches that accompanied them in their tombs upon their deaths. But it was their great wealth that ultimately undid the Inca. The Spaniards, upon reaching the New World, learned of the abundance of gold in Inca society and soon set out to conquer it - at all costs. The taking of Inca riches continues today with the robbery of sacred sites and blasting of burial tombs by grave robbers in search of precious Inca gold. 18

According to the excerpt, which of these was a concern in Inca society?

A.
banks and savings
B.
taxes on inheritance
C.
taxes on income
D.
invading forces