The fill in the blank is the separation of powers. Knowing this from the statement "<span>The power to enforce the rulings is vested in a separate branch of government than the power to issue the rulings."
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The union leader was : Grant
The confeserate leader was: Robert e. Lee
So with this equation, you have to work inside out with the parentheses. Firstly, solve 3+4: ![\{30-[12-7+2]*2\}-15](https://tex.z-dn.net/?f=%20%5C%7B30-%5B12-7%2B2%5D%2A2%5C%7D-15%20)
Next, solve 12 - 7 + 2: 
Next, solve 7 x 2, then 30 - that product: 
Lastly, solve 16 - 15, and your answer will be 1.
The correct answer to this question is this one: "D. having a rock concert in a public park in Japan"
The first three have a key point: requiring or changing by force. The last one just says having a rock concert in a public park in Japan. It's not forced, but voluntary whereas the first three are in a sense, forced.