What of the Following Is a Correct Distal Cause of the Spanish

What of the following is a correct distal cause of the Spanish defeat of the Incas?

A) The Spaniards had better weapons than the Incas.
B) The Spaniards had less exposure to domesticated animals than the Incas.
C) The Spaniards had horses for battle, whereas the Incas were on foot.
D) The Incas were historically exposed to more diseases than the Spaniards.
E) The Spaniards lived closer to livestock for thousands of years, unlike the Incas.