Explanation

The third blank must be consistent with the clue free expression. Circumscribed means restricted and would disagree with free expression. Jingoistic means extremely nationalistic and has a negative connotation. Unfettered means without restriction, making it the best choice for the third blank.

If America will always have a particular characteristic, then that characteristic must be always true. Egregious means extremely bad, and autonomous means self-governing, so neither of those words is a good fit for the blank. Immutable means unchanging and is your best choice. The trigger even in tells you that the first blank must go in a different direction from the second blank, and that you need a word that indicates changing.

Arcadian means peacefully rustic, and idiosyncratic means strange; neither of these words means changing and both choices can be eliminated. Volatile means prone to change, and is a good contrast to immutable.

Hence options C, F and G are correct!