If you were to break down Churchill's famous quote, you would see this:
Riddle, Mystery, Enigma. These three words are key. They are all connected. What is the connection --- these words describe a secretive and mysterious meaning. The best way to understand a puzzling quote like this is to break it down, and define each and every word; Forming a more understandable explanation.
I would choose non-polluting energy source and useful in remote areas - that is if there are plants and industries that are away from the general population.
Hello! The answer to your question would be as followed:
Hunter-gatherers
<u><em>b. moved constantly in search of food</em></u>
The Encomienda Policy confiscated land from native owners in order for Spanish conglomerates to have plantations.