What Was One of the Special Forms of Assistance Performed

What was one of the special forms of assistance performed by the colonial mestizos?

A) They paid taxes and helped the Catholic Church with the Inquisition.
B) They worked in the silver mines when no one else would.
C) They served as links between the Indian and Spanish populations.
D) They attended universities and brought their learning back to their homelands.
E) They would become military officers and alleviate manpower shortages for the Spanish.