1/3 of the deaths did not come from weapons, but from (also this is talking about in world war 1) (also if you put random stuff or links i will report)

Which act of the conquistador pizarro was crucial in overthrowing the inca? a. the destruction of the ancient inca city, machu picchu b. the siege of the inca capital near the cuzco valley c. the execution of the last inca ruler, atahualpa d. the unexpected deaths of 3 million inca warriors e. the murder of former inca emperor, huascar