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'm thinking of D but at the same time, A... But, I recommend D overall
Answer:
35 years or older because by then you'll be matured enough
A. The denied powers in the Constitution deny the state government the power to make treaties with foreign governments, coin money, and other things.
Hope this helps.