The correct answer is B) They assassinated the Incan emperor Atahuallpa.
The act of Francisco Pizarro and his men that ended the Incan Empire was that they assassinated the Incan emperor Atahuallpa.
Atahuallpa was the Emperor of the magnificent Inca Empire that had ruled the region for years. He was the 13th and last Emperor. Francisco Pizarro and his men captured him and killed him on August 29, 1533. Pizarro asked him if he preferred to die burned alive or strangled if he accepted conversion to Christianity. Atahuallpa decided to be strangled.