Which factors led to the decline and defeat of the inca empire? choose all answers that are correct. a. the inca's extensive efforts to protect their leadership succeeded. b. disease brought by the spanish devastated the inca population. c. the inca did not have the modern weapons and firepower that the spanish did. d. the spanish found many allies among the people the incas had conquered. e. the inca leader atahualpa was executed by the spanish.